Japan plans to create 10B 14-digit phone numbers with 5G era approaching(japantimes.co.jp)
japantimes.co.jp
Japan plans to create 10B 14-digit phone numbers with 5G era approaching
https://www.japantimes.co.jp/news/2019/05/14/national/japan-plans-create-10-billion-14-digit-phone-numbers-5g-era-approaching/
108 comments
But why would Japan run out of phone numbers with the population shrinking?
While of course IoT devices need to be addressable, that's more of an IPv6 problem than a phone number problem.... right? A person might have a few numbers, at most - and a flat if not shrinking number (I used to have home, work, cell; but have only had cell for a while now)
While of course IoT devices need to be addressable, that's more of an IPv6 problem than a phone number problem.... right? A person might have a few numbers, at most - and a flat if not shrinking number (I used to have home, work, cell; but have only had cell for a while now)
What do we have IPv6 for? I thought these 4G/5G networks run a TCP stack and telephony on top of it. Why do we phone numbers for device to device communication?
> Why do we phone numbers for device to device communication?
For billing, mainly.
The phone number in 3GPP protocols is the IMSI = international mobile subscriber identity, which identifies a user on the phone network. You swap out your SIM card, and you swap out your IMSI. You roam abroad, and the foreign network knows who to send the bill to.
The alternative would be to keep an international database of IMEIs (device IDs) like CDMA networks did. Using SIM cards with IMSIs ended up being more consumer-friendly.
For billing, mainly.
The phone number in 3GPP protocols is the IMSI = international mobile subscriber identity, which identifies a user on the phone network. You swap out your SIM card, and you swap out your IMSI. You roam abroad, and the foreign network knows who to send the bill to.
The alternative would be to keep an international database of IMEIs (device IDs) like CDMA networks did. Using SIM cards with IMSIs ended up being more consumer-friendly.
Probably the most accurate of all reasons for lack of options
Give me a call at [2607:f8b0:4004:802::200e] and I'll tell you.
A phone number is just an entry in my phone's address book - I don't think I dial them by hand any more often than I type an IP address by hand.
Exactly. I don't know my moms phone number. Or my sons. Or any friends or colleagues. The only phone number I remember is my childhood home phone number that was drilled into me 35 years ago, and my own number.
There are exactly 6 phone numbers I can recall from memory, one of them is my grandfathers which I’ve known since I was little, the others are family members on my phone plan because we got assigned a block of contiguous numbers when we switched to T-Mobile.
The last (originally a) land line phone number I had memorized in childhood was quietly lost last year when my grandmother passed away. That personally seemed to mark the end of the era where I'd ever remember a phone number that wasn't one I punch into random "rewards programs" kiosks as an ID of sorts.
Only robots make phone calls now.
I think this is an underrated comment. I think 99% of my phone calls now are robo-calls or organizations I've done some transaction with calling. Very few (1% or less) of my phone calls are like friends and family--other mediums just took those over completely.
In the grim future, you'll have a bot that can talk to your family and friends, like this with text to speech, using your voice:
https://www.theverge.com/a/luka-artificial-intelligence-memo...
https://www.theverge.com/a/luka-artificial-intelligence-memo...
I completely agree but the consideration is your phone is dead and you need to get ahold of someone. You should be able to easily memorize some way to contact emergency contacts IMO.
That's "8kEUuBoURjsxZ" in Base56.
Or using the PGP wordlist, "bookshelf amusement Vulcan phonetic crackdown alkali merit candidate aardvark Atlantic"
So obviously that's not going to work! But IPv6 isn't meant to be a static identifier. We have DNS for that.
I do think there's a future where the concept of "phone number" no longer exists. But this isn't it.
EDIT: Made it clear I agree with lemcoe9 that this doesn't work.
Or using the PGP wordlist, "bookshelf amusement Vulcan phonetic crackdown alkali merit candidate aardvark Atlantic"
So obviously that's not going to work! But IPv6 isn't meant to be a static identifier. We have DNS for that.
I do think there's a future where the concept of "phone number" no longer exists. But this isn't it.
EDIT: Made it clear I agree with lemcoe9 that this doesn't work.
Good luck with that. Numbers are easier to pronounce/use/enter. Not everyone uses latin.
> "bookshelf amusement Vulcan phonetic crackdown alkali merit candidate aardvark Atlantic"
Make some chinese, japanese, russians to pronounce this on daily base.
EDIT: __aardvark__ had to google this one.
> "bookshelf amusement Vulcan phonetic crackdown alkali merit candidate aardvark Atlantic"
Make some chinese, japanese, russians to pronounce this on daily base.
EDIT: __aardvark__ had to google this one.
[deleted]
You know someone is going to reserve "Longing, rusted, furnace, daybreak, seventeen, benign, nine, homecoming, one, freight car"
You could encode the addresses as 24 letters and numbers (a to z, case insensitive) but I'd say dns is probably a better solution.
Give me a call at metrix.afraid.org instead.
For the same reason we have DNS.
Considering
> about 32.6 million of the 80 million numbers starting with 020 had already been assigned
It seems a bit odd that they're putting the 14 digit numbers on the same 020 prefix that half the 11 digit numbers have already been released for. Seems like some chance for confusion where the first 11 digits collide. I'd have thought it'd make more sense to give a new 3 digit prefix for this class of numbers.
It seems a bit odd that they're putting the 14 digit numbers on the same 020 prefix that half the 11 digit numbers have already been released for. Seems like some chance for confusion where the first 11 digits collide. I'd have thought it'd make more sense to give a new 3 digit prefix for this class of numbers.
Someone mentioned they've been assigning prefixes in 020 to carriers in order. The thing to do then is make say 020 [0-3] be 11 digit numbers, and 020 [4-9] be 14 digit numbers. Then it's easy to validate.
I doubt they would assign 14 digit numbers where the 11 digit prefix was assigned to someone else, but, if they were desperate for space, they might make the 020 prefix all be maybe 11, maybe 14 and as 11 digit numbers were released, issue 14 digit numbers with the same prefix.
I doubt they would assign 14 digit numbers where the 11 digit prefix was assigned to someone else, but, if they were desperate for space, they might make the 020 prefix all be maybe 11, maybe 14 and as 11 digit numbers were released, issue 14 digit numbers with the same prefix.
How are these allocated under the hood? Wouldn't it make sense to stick all of these phone numbers in an IPv6 /64 at this point, with the "14 digit" just being a convention mapping to some range in that space?
Is a simcard always supposed to have the same ip ? How would ip spoofing would affect the phone network ?
Why not, a single /64 has way more address space than a MAC-48 and we've been permanently assigning those to hardware (including phones) for years.
I don't think the spoofing question would change based on what identifier you use. Whatever identifier you give you have to ask and answer the question.
I don't think the spoofing question would change based on what identifier you use. Whatever identifier you give you have to ask and answer the question.
It could even be cool to call someone by a domain name like an .id.jp that pointed to that address.
You mean something like 4.1.4.1.6.5.4.2.0.2.1.tpc.int ?
https://web.archive.org/web/20111014211308/http://www.tpc.in...
https://web.archive.org/web/20111014211308/http://www.tpc.in...
Nowadays I guess it's ENUM: https://danielpocock.com/a-quick-look-at-enum/
Regarding machine-to-machine communications, I'm wondering if these extra numbers are needed because mobile devices require a phone number to interface to mobile networks, even thought they typically only initiate data exchanges. Or‡ are there devices that actually receive phone calls - as in dial-up?
‡ not familiar with tech in Japanese infrastructure
‡ not familiar with tech in Japanese infrastructure
There are certainly cheap GPS trackers that send SMS messages. Of course, those are usually sold to consumers rather than into the M2M market.
M2M should just use IPv6 natively which would leave enough 11 digit numbers for human use.
And the fact that they are willing to go to 14 digit means they know that few people dial numbers manually anyway.
And the fact that they are willing to go to 14 digit means they know that few people dial numbers manually anyway.
In case anyone is wondering, ITU E.164 specifies that maximum length of a phone number is 15 digits:
* https://en.wikipedia.org/wiki/E.164
* https://en.wikipedia.org/wiki/Telephone_number
Given that Japan's country code is +81, that leaves thirteen digits for however Japan wants to assign it internally.
* https://en.wikipedia.org/wiki/E.164
* https://en.wikipedia.org/wiki/Telephone_number
Given that Japan's country code is +81, that leaves thirteen digits for however Japan wants to assign it internally.
Given that the population of Japan is <130M and is only going to go down from now on, what's the point? :)
14-digits?!?! Yikes. Not looking forward to using that!
14-digits?!?! Yikes. Not looking forward to using that!
For those that haven't RTFA Japanese phone numbers have 11 digits, 123-1234-1234, of which the first three are reserved as identifiers. A lot of people also carry two phones. Many companies also still have fax machines. Even my pocket wifi has its own phone number (can't be dialed).
8 digits is only 100,000,000 possible unique numbers. So it looks like they're simply running out of numbers.
8 digits is only 100,000,000 possible unique numbers. So it looks like they're simply running out of numbers.
>Japanese phone numbers have 11 digits
10 digit numbers are still in use:
https://en.wikipedia.org/wiki/Telephone_numbers_in_Japan#10_...
10 digit numbers are still in use:
https://en.wikipedia.org/wiki/Telephone_numbers_in_Japan#10_...
I've always thought of those as having an invisible 0 that's filled by the system, like when you call a landline number.
If the first three are reserved, why not just expand on those? There are sufficient 3 digit combinations for whatever they would need.
Good question. Who knows?
When Singapore ran out of phone numbers, they simply tacked on a single digit to every existing phone number. Japan's population is dwindling, that seems like a much easier option.
When Singapore ran out of phone numbers, they simply tacked on a single digit to every existing phone number. Japan's population is dwindling, that seems like a much easier option.
> 8 digits is only...
Sure, but the US with a much larger population only uses 10. 14 is bonkers, especially if it's just to preserve a method that basically wastes 3 of them.
Sure, but the US with a much larger population only uses 10. 14 is bonkers, especially if it's just to preserve a method that basically wastes 3 of them.
"identifiers" just means "area code", they're not wasted
As a user of this numbering system, this is how it generally looks like:
Landline numbers are dialed
0 - prefix to dial outside my area code
XX(X) - area code
XXX-XXXX - phone number
Mobile phones are
0 - prefix
70/80/90 - "mobile phones" area code
XXXX-XXXX - phone number
Since every number starts with a 0, you don't think of it as part of the number. Without the 0, most landlines are 9 numbers long and mobile phones are 10 numbers. When you're calling between landlines in the same area code, you only need 7 numbers.
The largest issue is the death of landlines and the rise of mobile phones. Lots of area codes dedicated to landlines when landlines are dying.
The NANP (north american numbering plan) is basically the only place in the world where cell phones get put into regular geographic area codes, due to the way cell phones are billed there (in the rest of the world, receiving calls on a cell phone is free, the caller pays the extra fees)
As a user of this numbering system, this is how it generally looks like:
Landline numbers are dialed
0 - prefix to dial outside my area code
XX(X) - area code
XXX-XXXX - phone number
Mobile phones are
0 - prefix
70/80/90 - "mobile phones" area code
XXXX-XXXX - phone number
Since every number starts with a 0, you don't think of it as part of the number. Without the 0, most landlines are 9 numbers long and mobile phones are 10 numbers. When you're calling between landlines in the same area code, you only need 7 numbers.
The largest issue is the death of landlines and the rise of mobile phones. Lots of area codes dedicated to landlines when landlines are dying.
The NANP (north american numbering plan) is basically the only place in the world where cell phones get put into regular geographic area codes, due to the way cell phones are billed there (in the rest of the world, receiving calls on a cell phone is free, the caller pays the extra fees)
Fyi, Mexico (+52) and Argentina +(+54) have mobile and landline integrated into the same geographic numbering, although there's an extra digit for dialing a mobile, to indicate cost (will be phased out in Mexico soon)
Brazil (+55) has mobile in geographic area codes, but separate prefixes within the area codes and longer than landlines (except for Nextel, which is a radio phone, not a mobile phone).
Some countries have been getting mobile phones in landline ranges as tarriff arbitrage, like Germany (+49) and Russia (+7, along with Kazakhstan, but I think it's only getting fuzzy in Russia). Others have been getting mobiles filtering in as fixed CDMA carriers using landline ranges start supporting mobile CDMA handsets (I forget where, but a few countries in Africa and southeast Asia)
Brazil (+55) has mobile in geographic area codes, but separate prefixes within the area codes and longer than landlines (except for Nextel, which is a radio phone, not a mobile phone).
Some countries have been getting mobile phones in landline ranges as tarriff arbitrage, like Germany (+49) and Russia (+7, along with Kazakhstan, but I think it's only getting fuzzy in Russia). Others have been getting mobiles filtering in as fixed CDMA carriers using landline ranges start supporting mobile CDMA handsets (I forget where, but a few countries in Africa and southeast Asia)
Maybe there will be a checksum digit. :) Given how rarely I enter contact information in manually, it doesn’t seem that unreasonable to have a larger phone number - nowadays it’s either clicking a link, opening a QR code, or copy pasting some text to make a new contact.
I would guess that these numbers will be hard-wired to "Internet of Things" devices, and this is a move to centralize the control of them. If every device has it's own telephone number that can't be modified and a 5G modem built in then the government (via phone companies) has a huge amount of control - sending messages, commands, remotely monitoring them, bricking them...
Every device on a 3GPP network (GSM/UMTS/HSPA/LTE/5G) already has a unique IMEI burned into it (and in most countries it's illegal to reflash the IMEI since they're used to ban stolen devices), phone numbers don't matter for "government control".
Can you address a device over a cellular network by it's IMEI number? I didn't think you could. You'd need a phone number as well. Could well be different over 5G though.
The IMEI is permanently associated with the device.
The phone number (IMSI) is associated with the SIM card (or eSIM now) and can be trivially swapped out.
A network can definitely address a device by IMEI only. For example in most countries you can make emergency phone calls to 911/112 with no SIM card in your phone (and hence no phone number) and there are no troubles routing that call.
The phone number (IMSI) is associated with the SIM card (or eSIM now) and can be trivially swapped out.
A network can definitely address a device by IMEI only. For example in most countries you can make emergency phone calls to 911/112 with no SIM card in your phone (and hence no phone number) and there are no troubles routing that call.
For 2G GSM the emergency calls are one big special case in the radio interface layer and do not really work as normal calls, this mechanism is triggered by dialing '112' which is hardcoded into the terminal (and does not work for other emergency service numbers, although US terminals maybe also special case 911, on European ones only 112 work).
IIRC BSC can page terminals on PCH not only by TMSI (which should be the normal state) but also by raw IMSI or IMEI, but this is not an capability that gets you anything useful as the terminal has to have active association to the network to even listen on PCH and when the device is associated the network knows the relationship between all of these three values.
IIRC BSC can page terminals on PCH not only by TMSI (which should be the normal state) but also by raw IMSI or IMEI, but this is not an capability that gets you anything useful as the terminal has to have active association to the network to even listen on PCH and when the device is associated the network knows the relationship between all of these three values.
The IMEI uniquely identifies the device; the IMSI uniquely identifies the subscriber.
https://en.wikipedia.org/wiki/International_Mobile_Subscribe...
https://en.wikipedia.org/wiki/International_Mobile_Subscribe...
15 is the ITU max BTW - something to be aware of for HN contributors when setting up DB Schemas that stope phone numbers.
Sorry for being cynical, but I've had my share of "things that would never happen because of standards/regulations/common sense" happen when you're storing data in DBs
Phones have at most 15 digits? I'm putting 20 or 25 just in case.
Phones have at most 15 digits? I'm putting 20 or 25 just in case.
> Phones have at most 15 digits? I'm putting 20 or 25 just in case.
That's fine, but if we have to go beyond 15 digits, it will probably be an upgrade as big as going to IPv6 128-bit addresses given that the ITU has specified fifteen for a while now:
* https://en.wikipedia.org/wiki/E.164
That's fine, but if we have to go beyond 15 digits, it will probably be an upgrade as big as going to IPv6 128-bit addresses given that the ITU has specified fifteen for a while now:
* https://en.wikipedia.org/wiki/E.164
A system I worked on used the RDBMS’ default of 50 characters in a varchar column and the validation regex allowed uppercase alphanumeric input (for “1-800-CONTACTS”-style numbers) and also allowed spaces in addition to dashes. But the system didn’t allow users to label numbers in a separate field - so the users put the labels at the end of each number, e.g. “425-123-7890 JOHN SMITH, HOME”.
The system used this value for generating tel: links in webpages - which meant the links wouldn’t work anymore - but users preferred keeping these custom labels to having Skype-integrated or iOS tappable links anyway.
/csb
The system used this value for generating tel: links in webpages - which meant the links wouldn’t work anymore - but users preferred keeping these custom labels to having Skype-integrated or iOS tappable links anyway.
/csb
”The communications ministry plans to create some 10 billion 14-digit phone numbers starting with “020” for assignment.”
I expect “020” isn’t currently a valid prefix in Japan. If so, this makes it a lot easier for software to know whether it has to wait for more digits in a phone number.
There probably are lots of other unused three-digit prefixes, but one has to assume what one deploys now will stay around forever (one century and counting), and that the future will demand space for things we have no idea of.
And 14 isn’t that bad. Bank accounts in Gibraltar (population 35,000 or so) have 23 characters, Kuwait’s (population 4,5 million) have 30, Malta’s (population about 500,000) 31 (https://en.m.wikipedia.org/wiki/International_Bank_Account_N...)
I expect “020” isn’t currently a valid prefix in Japan. If so, this makes it a lot easier for software to know whether it has to wait for more digits in a phone number.
There probably are lots of other unused three-digit prefixes, but one has to assume what one deploys now will stay around forever (one century and counting), and that the future will demand space for things we have no idea of.
And 14 isn’t that bad. Bank accounts in Gibraltar (population 35,000 or so) have 23 characters, Kuwait’s (population 4,5 million) have 30, Malta’s (population about 500,000) 31 (https://en.m.wikipedia.org/wiki/International_Bank_Account_N...)
Except that there are already 11-digit 020 numbers in Japan, so hopefully it'll be something like 0200..0202 11-digit and 0203..0209 14-digit. Otherwise you'd need a database lookup already just for the length of the number.
> For “internet of things” devices, 11-digit numbers starting with “020” have been used since January 2017.
> For “internet of things” devices, 11-digit numbers starting with “020” have been used since January 2017.
Machine-2-machine (M2M) communication might play a role in the big number of addresses, not sure though.
You are correct, the 020 prefix is exclusively reserved for M2M. The "conventional" 070, 080 and 090 prefixes are used for smartphones & M2M and the Japanese government has tried to move the vast majority of M2M to 020. It was already expected that the current 11 digit number for 020 is not sufficient, and AFAIK there is a plan for numbers up to 14 digits.
> Not looking forward to using that!
I thought that as well, but the more I think about it..: I'm pretty sure I did not type out a phone number for the last 5 years.
It's all numbers already saved in my contacts, new numbers I got via some form of text message or numbers on websites and the Google app.
It might be that people don't really type number all that often anymore.
I thought that as well, but the more I think about it..: I'm pretty sure I did not type out a phone number for the last 5 years.
It's all numbers already saved in my contacts, new numbers I got via some form of text message or numbers on websites and the Google app.
It might be that people don't really type number all that often anymore.
At some point we should stop using numbers and use something like an email address.
Indeed. Using self-descriptive "handles" or usernames such as @name.surname or @company.city would be great for caller and texter identification, as well as user discovery--if they want it to be public, that is. That, and having to send a request before you can contact anyone would bring some control and protection back to the user.
Incidentally, this is already possible with SIP, which is behind most standardised VoIP signalling. In particular it allows for federation too.
if we're going to reinvent PSTN, can we also include in that specification an arbitrary length numeric passcode that a number owner can set, and reset, to require for the call to ring through, or even return the SIT if the passcode fails?
What's wrong with case insensitive letters?
US-ABC-900-900 can be a beautiful phone number and global. 165,216,101,262,848 numbers per country.
US-ABCD-900E-900R in case we run out of numbers again.
US-ABC-900-900 can be a beautiful phone number and global. 165,216,101,262,848 numbers per country.
US-ABCD-900E-900R in case we run out of numbers again.
Most countries don't use the English alphabet, so I'm not sure if that would work outside the US.
Most countries don't use the English alphabet
I strongly suspect that most countries (and certainly a majority of the world population) use a super-set of the English alphabet though.
I strongly suspect that most countries (and certainly a majority of the world population) use a super-set of the English alphabet though.
Your suspicions are incorrect. Only 36% of the world’s population uses the Latin alphabet.
https://www.worldstandards.eu/alphabets/
https://www.worldstandards.eu/alphabets/
Even digits can be written differently in other languages.
https://www.omniglot.com/language/numerals.htm
https://www.omniglot.com/language/numerals.htm
India is really carrying the torch for using lots of different alphabets.
It would be incompatible with everything that already exists
14-digit!? No one can possibly remember that easily... Why not alphanumeric and make the address space so big that people can chose one that would be possible for a stranger to remember immediately - like we have domain names, e.g.: cecelia_alberto OR charlotte1231
Does anybody actually remember phone numbers these days ?
Edit : I do remember the half a dozen I use or might really need, and already feel like an outlier. ( And as pointed in another comment, they're already 11 digits each. Not that much of a difference. )
Edit : I do remember the half a dozen I use or might really need, and already feel like an outlier. ( And as pointed in another comment, they're already 11 digits each. Not that much of a difference. )
I'm 18, the only number I remember is 08456060973 because it was used for a radio show I used to listen to and they'd repeat it constantly. I seldom communicate via the telephony network, if I need to call someone I call them on Telegram, my mum uses Viber, my Dad uses Skype, and if I need to message someone there's more than enough options for that.
> Does anybody actually remember phone numbers these days ?
Yup, all the ones I knew as a kid in the 80s and early 90s, and haven't used for 2 decades.
Yup, all the ones I knew as a kid in the 80s and early 90s, and haven't used for 2 decades.
Same here, indeed. And for 3 decades too.
> Does anybody actually remember phone numbers these days ?
Children do, or should. Even very young children should be taught until they have memorized their own phone number.
And even older children might not have phone yet, but still need to be able to call home.
Children do, or should. Even very young children should be taught until they have memorized their own phone number.
And even older children might not have phone yet, but still need to be able to call home.
I wonder if parents these days just put "Mom" and "Dad" contacts in their kids' phones and don't bother teaching their kids their phone numbers
I have had the same number for 10 years. A few months ago I made a conscious effort to remember it since I was getting fed up of referring back to my contacts list on a daily basis.
No, properly not perhaps. But it would be a nice feature when you have to exchange phone numbers.
We exchange cards as a matter of daily interaction. The biggest issue is reading properly a name ( kanji ), not the other data in them.
[deleted]
I haven't learned a new phone number in almost 14 years. And the ones I do know are all in the same area code, so I really only have to know 7 digits each.
> 14-digit!? No one can possibly remember that easily...
I have no problem at all remembering my 22-digit IBAN. I know people who memorize random-generated 30-character passphrases. But yeah, we don't seem to be the norm.
I have no problem at all remembering my 22-digit IBAN. I know people who memorize random-generated 30-character passphrases. But yeah, we don't seem to be the norm.
> Why not alphanumeric
Because that mean re-inventing the phone system and making it incompatible with all existing and future devices made for the whole rest of the world.
These are going to be for 5G IoT devices anyway, the phone number is just going to be for billing use, all the actual traffic is going to be over IP
Because that mean re-inventing the phone system and making it incompatible with all existing and future devices made for the whole rest of the world.
These are going to be for 5G IoT devices anyway, the phone number is just going to be for billing use, all the actual traffic is going to be over IP
The numbers are for machine-to-machine communication. No one will be calling them.
Memorising peoples phone numbers is about as ridiculous as memorising ipv6 addresses, sure you can do it, but what's the point? You've got a perfectly capable computer in your pocket to remember it for you.
You were involved in an accident and your phone was destroyed. Your doctor asks you who they should call. Now what?
Insurance has my emergency contacts
Could you log in to social media and message someone? Or log into google/apple/yahoo and check your contacts?
No, because my password is in my password manager, and I need my (now destroyed) phone for 2FA.
A battery powered device which is prone to failure / running out of power
What exactly are you going to call them on if it does?
I remember 12 digit IP addresses all the time
[deleted]
- 070, 080 and 090 prefixes are being used for mobile phones and M2M (machine-to-machine) communications since 1999. They are 11 digits long and the future shortage was expected.
- 020 prefix was created exclusively for M2M in 2017. The existing M2M numbers do not have to migrate, but it is recommended for most cases as 020 prefix has no requirement for the number portability and QoS. So the creation and expansion of 020 prefix is irrelevant to the population estimate.
- Since 0204 prefix was already used for pagers, and since 0 is a trunk prefix in Japan, there were initially 80 million numbers available, starting with 0201--0203 and 0205--0209.
- It was envisioned that 80 million numbers do not suffice for the future expansion of IoT devices, so there was already a plan for 13- or even 14-digit numbers at the time. Note that while 14-digit numbers are within the E.164 recommendation (e.g. +81-20-XXX-XXXXXXXX = 020-XXX-XXXXXXXX) it does seem to cause some serious engineering problems to tackle.
- 020 prefix was allocated in the increasing order, so numbers up to 020-536-XXXXX are allocated as of May 2019 [1]. It is expected that the digit expansion will happen in the remaining area.
- While 020 will greatly postpone the exhaustion, existing 070--090 prefixes would be eventually full in the future. 030, 040 and 060 prefixes once used but now vacant are reserved for this inevitability.
[1] http://www.soumu.go.jp/main_content/000477284.pdf