You can use iMessage if you use it with only data but that does limit your ability to only using iMessage with other iMessage users. When you put the Programmable Wireless SIM in your phone you'll be prompted to associate that number with iMessage, if you deny it, then you it won't pick up that number on the SIM with iMessage. I personally use this solution when traveling out of the country with a Programmable Wireless SIM in my iPhone. It "works" but unfortunately in a limited manner (i.e. data only).