"The call connects and the other party can hear me, but I can't hear them."
This usually means the incoming audio is not reaching the device and could be a problem with NAT traversal. You can try to bypass NAT traversal by adding a STUN Server.
1. Tap on settings, then SIP Accounts, then your SIP Account. Tap on advanced settings, then NAT traversal. Try with it set to Auto, Off and STUN. Try each option with Discover Global IP set to internal and then with Discover Global IP set to external.
2. You should also check to see if your provider has a NAT proxy that you can use. If so, remove the STUN Server and enter the details in the Proxy field (not outbound proxy) in the advanced settings. If they specify a port, put it at the end of the proxy prefaced by a colon (e.g. example.com:5080).
3. If you still have an issue, you can send a SIP Log for us to review. Tap on settings, then preferences. Turn Log SIP Traffic on. Tap done, then restart the softphone. Make a call and confirm you have the same issue. Then go back to settings and tap on SIP Log. Tap on Send to Acrobits and include your name in the note. Then open a ticket and state that you have followed the instructions in this article and have sent a log.*
*If the problem is exclusively on 3G, please state this in the ticket. There are many cellular data providers that still don't handle SIP very well. For example, STUN queries often fail over 3G networks. We may still be able to resolve the issue, but knowing in advance that the issue is exclusive to 3G will save both you and us time.
keywords: audio, sound, inbound, incoming, receive, acrobits, softphone, groundwire