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Moving a call centre to a sip voip setup

Moving a call centre to a sip voip setup

Moving a call centre to a sip voip setup


I work in a 40 seat call centre, ive implemented a few remote workers with a voip setup using a hosted ip-pbx (independant from our inhouse system which is quite dated).

As were in the UK the call centre uses NTL ISDN lines which is quite expensive. Ive found a sip provider giving us much cheaper phone calls, and will be moving some of our office workers to the voip system as a test (using hosted pbx).

Though we will keep the NTL lines in the interim. Moving forward we are thinking of moving to a total voip / sip solution, getting an asterisk based pbx inhouse, can someone tell me what bandwidth would be required for say  55 lines open at once?

Will use of G729 reduce the requirment of each line to sub 50Kbps each way?
Is a sdsl connection a decent internet connection to rely on for this?

Hope someone can advise on the implications of this.



RE: Moving a call centre to a sip voip setup

G729 uses about 20k from memory, so 20kb/s x55 = 1.1Mb/s
You'll also need internet connectivity, of course, so as long as you get a service that's better than 1.1Mbs (both directions) and your service provider offers class-of-service to prioritise your VoIP traffic, you'll be OK.
Some sort of 10Mb/s connection should do it?
The bandwidth required by VoIP is really very small, it's the quality of the service that really matters, and getting properly qualified network people in to:
 - install the VoIP system
 - ensure QoS is working
is the really important bit.
You can usually tell a VoIP supplier is rubbish if their proposal doesn't include an intelligent detailed design - if their "architect" has no idea what he's doing, he just cuts'n'pastes bits of sales brochure and bits of manual together for the proposal - steer clear of them if they do that.

RE: Moving a call centre to a sip voip setup

Be careful....

You have to understand that using G729 will have a drop in quality compared to your ISDN.
Although not a great deal, as soon as you get any sort of issue with your connection (jitter, dropped packets etc) is is much worse on 729 than on 711.
Also remember to get your stats correct. For exapmple 64k G711 is one way only without overheads of IP. So two way is really about 160K

Have a look here...


You have to work out, how many agents are on the phone at one time, how many calls are stacked up playing MOH etc etc... the work it from there.


Robert Wilensky:
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.


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