Major issues

It calls the last person I talked to immediately after the other party hangs up. If it lost my sip service at the time, it will use my cell service which costs a lot o money. It does this in the background. I tested other sip programs with the same VoIP provider and this does not happen. Also, the app has major issues with restarting from the background.

DKommerz about iSip -VOIP Sip Phone, v4.8.2