Oneway audio

[bilbotel]

We have one mitel 3300, single site.
I am trying a softphone for the first time, in this case microsip using my pc to test. The mitel and phones are on a different voice vlan to computers.
When I call a mitel ip phone from microsip both of which are connected to the same physical switch, I cannot hear the phone that I dialed but they can hear me fine.
If they don't answer and it goes to voicemail I hear the greeting and can record a message no problem.

If I make an external call to the same phone  from microsip the sound is fine, as are calls to all other external numbers.

So seems like the problem is microsip to ip phone call . Given that there is no firewall involved as on the same physical, what could it be? Codec or network issue of somesort?

Any troubleshooting suggestions?

[acejavelin]

How are the two subnets routed to each other?

The key here is station to station audio does not touch the Mitel controller, it goes direct from device to device... if you are getting one way audio when calling station to station on two different VLANs, then something is stopping one leg of audio.

You say no firewall is involved, so the first thing I would check in this case is that the gateway the phones are using is correct for the voice VLAN to talk to the data VLAN you are connected to...

[bilbotel]

It does appear that the phones do not receive a gateway ip from the mitel server when checking the network config on the phone, the mitel server itself has one specified which now makes sense that it is reachable and external calls work from the softphone.

Where do you specify the gateway on the mitel, I cant see an entry in DHCP leases, or any of the DHCP settings as would be the case with a Win DHCP server, is it a DHCP option?

Also is there any reason why the telecom provider would have left it like this? Security, or may simply because it was not needed at the time?

[bilbotel]

Added DHCP option 3 on the Mitel server and it has resolved the issue, many thanks.