WiMax: Any good for VOIP??

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old3eyes

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#76359 1-Feb-2011 13:19

Hi ,

We have a customer with a PBX system that has it's VOIP trunks connected via WiMax. They constantly complain about the bad speech quality. I've looked at the system config for the SIP TK codec and it looks normal as any G711 setup and QOS is set. When this was first flagged we didn't know that they were using wireless and if my own testing here with Vodafone and Telecom data sticks is anything to go by I'd give wireless a miss for SIP trunking.

Anyone else using this sort of setup??

Regards,

Old3eyes

Ragnor

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#433777 1-Feb-2011 16:37

What ISP? What do pings and tracert's look like to the SIP providers servers/hosting from the clients end?

Kiwipixter

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#433791 1-Feb-2011 17:02

old3eyes: Hi ,

We have a customer with a PBX system that has it's VOIP trunks connected via WiMax. They constantly complain about the bad speech quality. I've looked at the system config for the SIP TK codec and it looks normal as any G711 setup and QOS is set. When this was first flagged we didn't know that they were using wireless and if my own testing here with Vodafone and Telecom data sticks is anything to go by I'd give wireless a miss for SIP trunking.

Anyone else using this sort of setup??

Wimax is quite different from HSPA wireless technology, and Wimax hardware quality is usually better than the USB sticks you are talking about. Wimax has higher bandwidth and lower, consistent, latency than HSPA. So running voip over wimax should be better than over HSPA, in theory. In practice, however, the performance of wireless technologies depends on many factors, most of them are environmental.

I'd recommend testing the wimax connection and pbx config. e.g. is G711 the right codec to use?

sbiddle

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#433809 1-Feb-2011 17:45

WiMAX has great QoS and has different service classes for different traffic types. VoIP (and other real time traffic) works brilliantly when configured properly.

If things are configured properly VoIP traffic will be tagged with DSCP or 802.1p and carried as a CG or RT traffic type over the air interface.

antoniosk

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#433969 1-Feb-2011 21:58

If things are configured properly VoIP traffic will be tagged with DSCP or 802.1p and carried as a CG or RT traffic type over the air interface.

I have bolded and underlined the keypoint. My experience with wimax is that it's a fragile and fickle technology and VERY intolerant to poor setup or deviation in the airlink performance.

It's ok for data and internet where timing isn't really relevant. But for voip or other realtime traffic... yikes...

________

Antoniosk

sbiddle

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#433976 1-Feb-2011 22:08

antoniosk:

If things are configured properly VoIP traffic will be tagged with DSCP or 802.1p and carried as a CG or RT traffic type over the air interface.

I have bolded and underlined the keypoint. My experience with wimax is that it's a fragile and fickle technology and VERY intolerant to poor setup or deviation in the airlink performance.

It's ok for data and internet where timing isn't really relevant. But for voip or other realtime traffic... yikes...

Do you need some Alvarion training? I might know somebody who could help!

old3eyes

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#434798 3-Feb-2011 13:11

Thanx people for your thoughts. I have passed the thread on to the techs concerned and let them take it from there..

Regards,

Old3eyes