I'm having issues with our IP phones (DSX VOIP 34B). I have everything to default settings, but audio is only working one way. The IP phone can not hear the other side, but the other side can hear the IP Phone.

However, if I use the same settings/login/ext with X-Lite (from my laptop), it works perfectly. Both my laptop and the IP Phone are on the same switch, so I don't think it's a networking issue. For now this is all LAN based.

The DSX system is running v3.34. The system has a static IP reserved from our DHCP server. For the SIP port, I'm using the default 5060. For the RTP Range Start I'm using 1024 (the RTP Range End box is greyed out and shows 1215, which seems odd).

A few more notes. When I leave the phone RTP port at default (which is 3462), it will do the one way audio (see above), but if I set it to 1024, there is no audio (yet it will ring and dial out). I ran wireshark while running X-Lite and can see it's using RTP port 1080. If I set the IP Phone to use 1080 it will behave the same as using 3462, again only one way audio. (Again note that X-Lite works perfectly with two way audio).

I've tried a factory reset of the phone, didn't change anything. Phone HW Stats:
Hardware Ver 9.1.3.5
Firmware Ver 1.0.7.2

Any ideas? help