csipsimple is a very good sip client software in Android, we often suggest our customers to use it if they want to deploy voip network with Android phones.
As we know, there are always one-way or no-way audio problem. To solve this problem, STUN should be configured in softphone. But some customers often response it is hard to set STUN in csipsimple.
In fact, it is easy to do that. Please follow below steps which are described in csipsimple website too:
(1) Go on setting Settings > Network – Tick “Use Stun” and fill a stun server on the field bellow. If you are cloud-mss subscriber, you can use your virtual server address as your STUN server too. Of course, you can use csipsimple default STUN server.
(2) You can also try to use ICE in addition to STUN if STUN alone doesn’t solve the problem : Settings > Network – Tick “Use ICE”.