catalist 3650 doesn't pass voice

Bekzod Fakhriddinov · ‎05-23-2013

|_voip PBX___|-----|__3650___|------fiber-------------|__3650_____|------|_voipphone__|

. Hi guys I have a case where voipphone is registered on the voippbx but peaple on both end can't hear each other . No ACL on both 3650 , no firewalls between them , distance is about 2 miles . I tried to make telnet x.x.x.x 1720 or 1719 or 1721 (h323 ports) to opposite switch -connection refused . I have no idea ..

How can test if ports are open on the 3650 ?

Is it coorect If I create allowing acl and apply it on both 3650 on the interfaces connected one switch to voippbx "IN" , second switch on the interf connected to voipphone "IN" ?

Julio Carvajal · ‎05-23-2013

Hello Bekzod,

If there is no ACL in place then there should not be any need to create it one in order to allow the traffic,

The phone can register with the PBX so Routing is good,

I would encourage you to doble-check the path between source and destination to make sure that traffic is indeed traversing the entire network (You could create captures as close to destination and source as possible)

Regards,

Julio

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Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC

RUSTOM BILLIMORIA · ‎05-24-2013

Hi Bekzod,

I would try to light your way here.

Firstly, the phones registering with the PBX has nothing to do with them communicating with each other. The phones registering with the PBX means that the path from Phones to pbx is good. But when the phones communicate with each other, they do not communicate with through the PBX/cucm. They establish a RTP session between them. Maybe, the routing between the phones is not done. Do not assume that just becuase the phones register, they would speak to each other. Secondly, a telnet from one end to the other using H323 ports would be denied by the device, even if there was a route, if the device is not expecting the telnet to happen on a port apart from port 23. So when u say that the telnet fails, it does not mean that the packet can not go throuh the network.

Maybe a simple troubleshoting step might work. Replace the phones with computers in the same network and see if they can communicate with each other. if yes, then further troubleshooting is required. But i still suspect routing and issue rather than the voice packet not flowing as per experience. But maybe some more troubleshooting would suffice.

Rustom Billimoria

Bekzod Fakhriddinov · ‎05-24-2013

Hello guys , thank you for ur attentions . I did same setup in our office lab , we have 2 catalist 3650 and 2950 and it works with no problem , then I play around with settings on VoIP PBX and it's look like fixed , it's look like was a problem with on phone system not on the switches . I am not sure yet customer must check again but first test got it trough .

Thank you again.