Go for Bria, its the best!
I tested a lot of SIP Apps during the past years and I have to say Bria is the best!
- multiple SiP numbers
- High Q phone calls over 3G and 4G (wifi too)
- recording function
- conference calls
- stable version / no crashes
- really easy to use
I use Bria every day for the last three years and I love it!
Go for it, its worth it !!!
Dr_Smart about
Bria iPhone Edition - VoIP Softphone SIP Client, v3.6.2