ARKFone Lite is Audio / Video next generation SIP based softphone. It is a generic SIP client for iOS 4.0 or higher versions. It can work with any SIP server through any type of network, such as 3GPP LTE, GPRS, and Wireless LAN (WiFi), CDMA2000 or fixed line. It supports the following codecs
Supported Audio Codecs:
G.711 (PCMA, PCMU) , G.722 , AMR-NB-OA , AMR-NB-BE, GSM ,Speex (8Khz),Speex (16Khz),Speex (32Khz)

Supported Video Codecs:
H.263, H.264, 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 works with any standard SIP proxy.
Main features:

* Making and receiving VoIP audio and video calls.
*Sending and receiving Instant Messages.
* Connect to any standard SIP video phone.
* Connectivity through WiFi and 3G
* Integrated contacts from the phone
* Loudspeaker
* Favorites
* Time, call status logs
* Last calls log
* Redial
* Work in background mode (only with servers allowed SIP via TCP)
* Multiple accounts support

Note:

1. You need to have an account from a VoIP provider 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