1) User friendly interface
2) Dialer supports SIP for signaling.
3) Dialer supports G729, G723.1, iLBC codec for sending audio data.
4) Dialer should be able to run behind NAT or on private IP.
5) client can hear remaining balance by listening to IVR
6) Dialer should able to support GPRS, WiFi,3G network and Blue tooth for internet connectivity.
7) Dialer should able to run on the phone having Symbian or Windows Mobile 5 and 6 and J2ME.
8) Dialer should be fully customizable.
9) Dialer with any kind of Soft switch which support SIP (SER/OpenSER/Asterisk)