voip gateway gsm cli spoofing + symbian, android, iphone mobile dialers to work in voip blocked countries

I am hosting a voip gsm gateway in an asian country, i want to be able to spoof the gsm caller id to any other digits part from its own but my netwrok provider doesnt allow it. I am using a class 5 switch with the voip gsm device. Also i need mobile dialers to work in countries where sip is blocked for clients to be able to connect to my voip gsm gateway.