Aastra 9143i sometimes drops calls

[mxtek5]

Hey guys, i got a client running PBX in a flash with and two of the phones seem to either drop calls or cut in and out while on a call.
What are some recommendations for things i should be checking?

Thanks in advance, this forum is a great and very resourceful place!

 

[mxtek5]

Just got off the phone with the client, it seems that they can make calls, but it sounds like the person on the other end goes silent and then starts talking again, in other words, they can only hear every other word, and this doesn't happen all the time, strange...

 

[randy7376]

You may want to look at the silence suppression on the Aastra phones. What firmware version are you running?

Per the Aastra Administrators Guide Release 2.6, page 4-107:

Silence Suppression
In IP telephony, silence on a line (lack of voice) uses up bandwidth when sending
voice over a packet-switched system. Silence suppression is encoding that starts
and stops the times of silence in order to eliminate that wasted bandwidth.
Silence suppression is enabled by default on the IP phones. The phone negotiates
whether or not to use silence suppression. Disabling this feature forces the phone
to ignore any negotiated value. You can configure silence suppression on a global-basis using the configuration
files or the Aastra Web UI.

I would suggest you manually change one phone from it's web interface and disable silence suppression and see if you problem goes away. If so, then you can enable it globally for all the phones in aastra.cfg.

EDIT: Just checked Release 3.2 of the Administrator's Guide and it says essentially the same thing as above. Add

 sip silence suppression: 0

to aastra.cfg to disable globally if after testing it works.

 

[mxtek5]

You may want to look at the silence suppression on the Aastra phones. What firmware version are you running?

Per the Aastra Administrators Guide Release 2.6, page 4-107:
I would suggest you manually change one phone from it's web interface and disable silence suppression and see if you problem goes away. If so, then you can enable it globally for all the phones in aastra.cfg.

EDIT: Just checked Release 3.2 of the Administrator's Guide and it says essentially the same thing as above. Add

 sip silence suppression: 0

to aastra.cfg to disable globally if after testing it works.

So basically your saying to disable silence suppression, that is likely the cause on those phones?

 

[jmullinix]

A buddy of mine is having this problem. We are still in the diagnosis phase, but it is beginning to look like the network switch is failing. In his case, the audio stream will stop for 30 seconds at a time. When he put the phone on another switch, the problem went away.

 

[randy7376]

I'm saying, based upon the symptoms you described, that this is something easy enough to try on one phone and see if it resolves your problem. There are certainly endless possibilities as to why!

John brings up a good point, also. The quality of your network equipment and cabling plays a large role. If you're buying your network switches at Best Buy for $50.00, you're bound to have a problem sooner rather than later.

We use Cisco and HP ProCurve, primarily. I've only ever had an issue with one ProCurve in the last six years. The PoE power supply kept dropping power randomly. Since the ProCurves have a lifetime warranty, it was swapped out and problem solved.

 

[mxtek5]

They re using a Linksys 24 port and D-Link 24 port switch, neither of which i have ever had problems with before. I am heading there shortly and will test your recommendations. Thanks Randy

 

[mxtek5]

UPDATE: The phone is a 9112i that is having the problem.

I noticed that all the phones on the network have the basic codecs (G.711 u-Law, G.711 a-Law, G.729) Enabled. I will enable them and see if that makes a difference. Anyone thinks that could be the problem there?

The ones working fine also have Explicit MWI Subscription enabled, any thoughts on that?

About silence suppression, all the other phones have that enabled and they work fine, so it would be highly unlikely that disabling it would cure the problem