OTEL 1

the author of this app says:

OTEL is a softphone running on Iphone.

Features
Making and receiving SIP calls
Built-in tunnel for passing thru voip blockades *
Connectivity through WIFI, 3G, EDGE and GPRS
Integrated contacts from the phone
Loudspeaker
Favorites
Balance information **
Destination, rate **
Time, call status logs
Last calls log
Redial
Support for codecs g729, GSM and g711
Compatible with IPod and IPhone 2G/3G

For more details please visit www.otech.ne.jp

Requirements

Requires iPhone OS 3.1 or later.