MORPhone

It is a generic SIP client for iPhone/iPod/iPad
Supported Audio Codec:

G.729, G.711 |(PCMA , PCMU), G.722 , G.729, GSM, Speex (8Khz), AMR-NB-OA, AMR-NB- BE
Supported Video Codec:

H.263, H.263-1998, H.264-BP10,H.264-BP20, H.264-BP30, Theora, MP4V-ES, VP8
Video will work on the normal SIP stack without any configurations on the standard SIP server
Tested SIP servers:

Cisco CUCM, Cisco CME, Asterisk and OpenSIP also work with any standard SIP proxy.
Main Features:

Making and receiving VoIP audio and video calls
Connect to any standard SIP video phone
Connectivity through WiFi and 3G
Integrated contacts from the phone
Loudspeaker
Time, call status logs
Last calls log

Note:
1. You need to have MOR account in order to use this software.
2. Please, check your cellular operator's terms of agreement to make sure they allow sip calls on their network