Odd ring tone,then one way audio with voxalot on Nokia e65
 

I've got a Nokia e65 and a voxalot account with a sip account from engin. Sometimes it all works well together but most times I get a single tone ring. When the call is answered they can hear me but I can't hear them. At other times I hear a 'trilling' ring and all works well with both parties able to hear each other. I feel like I have been chasing gremlins with the sip settings so if anyone has an idea as to what is going on here I'd love to know about it. Oh yeah...I use a huawei e5832 modem and the au.voxalot.com

The problem "can't hear them" may be due to a incorrect media address given in a SIP SDP packet at some point in the chain from your E65 to Voxalot to Engin. Example; Your E65 is behind your mobile provider's NAT and the E65 sends a LAN IP address as the media contact address. In this case the remote party's audio will not reach you because the packets are addressed to a non-routable LAN address.

To attempt a fix I suggest you first set "Symmetric NAT Handling" = yes, then do call tests both with and without using a STUN server in your E65 settings. Ordinarily it's better to use a STUN server in order that your E65 can use it's public IP address and port number inside SIP packets, however if that doesn't work out well (due to symmetric NAT or something like that) then you will want to tell Voxalot to carry the voice packets instead of trying to send voice directly to and from the remote party (engin). In order for Voxalot to carry the voice packets you must do two things; First, set "Symmetric NAT Handling" = yes, AND do not use a STUN server.

Not using a STUN server causes certain 'errors' inside the SIP SDP packet which signal Voxalot to compensate by carrying the voice packets.