[asterisk-users] random one way audio and noise between SIP phones on same LAN

[Brian Candler]

On Wed, Oct 18, 2006 at 01:44:06PM +0200, Giorgio Incantalupo wrote:
> sometimes I have one way calls and noise between sip phones connected to 
> the same LAN so no nat/firewall is involved. I tried with different sip 
> phone models soft phones and the result is the same. I searched inside 
> every log file but found nothing.

Plug everything into a hub, not a switch, and then run tcpdump to look at
the traffic going back and forth:

# tcpdump -i eth0 -n -s0 -v

Look at the RTP packets, in particular source and destination IP addresses.
Do they go phone1->phone2 and phone2->phone1 ? Or do they go phone1->PBX,
PBX->phone2, phone2->PBX and PBX->Phone1 ?

In the latter case, it's not the phones which are at fault, it's your PBX.

If the PBX is Asterisk, and you want help solving the problem, then you'd
better give full details of your system (hardware and O/S platform, asterisk
version, how it's configured)

If you want the streams to go direct between phones, and the PBX is
Asterisk, then set "canreinvite=yes" in sip.conf

> Considering to monitor a remote PBX via ssh, which  text-only 
> application  could  I use?

Depends what the PBX is. If it's something with a serial console, then
minicom, tip or cu will let you talk to it. If it's asterisk, then use the
asterisk console (asterisk -r)

HTH,

Brian.