Julien Vehent on 3 Jun 2011 15:30:05 -0700

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Re: [PLUG] VoIP setup

On Fri, 3 Jun 2011 18:09:21 -0400, Joe Terranova wrote:
SIP phones, also investigating softphones.

Ok, if you do digital the whole way (SIP or softphones, and a SIP
provider), you don't actually need any special hardware. You'd want to
get a decent server, and that's about it.

30 ! :) It's a call center, they are more people than that, so it's a safe
estimate, but it would possibly grow bigger in the next 2 years.

Ok, so your issues are going to be bandwidth, and providers that can
handle that many simultaneous calls.

For a SIP provider, there are a lot of choices. You want one that will
give you a lot of simultaneous channels.

Originally, the decision was to stay on analog and to the analog termination in the PBX, then run on plain old copper. So no SIP Provider, but I want to leave the option open.

I'm guessing you only really need one phone number? If you want with
someone like VOIP.ms, this is how much that would cost:

So you'd be paying like $1.50 a month for the number, and then paying
between 1-2 cents per minute for incoming and outgoing calls. Their
limit on simultaneous calls is 25, but they'll increase it if you
contact them.

That's what I was thinking. Right now, our average cost per minute is around 10c. That would make a good saving.

The remaining issue is bandwidth. You're looking at between 8 and 20
KBps per call. I average around 10 kbs, with ulaw. G279 is lower
bandwidth, but isn't free (you'd have to get a license from digium to
use it). GSM is also low bandwidth, (8kbps), but is cell phone
quality. You can see VOIP.ms' supported codecs here:

So if you want with ulaw, you would need around 368 KB / 2610 kb per
second. If you want with GSM, 108 KB / 870 kb per second

GSM quality is the bare minimum. I should probably test that before deciding, but I was estimating the bandwidth around the same level as you. A couple of T1 should do the job.

In summary, you don't need special hardware but a decent server, you
want a SIP provider that supports 30 simultaneous calls without
costing you a ton, and you need to be conscious of your bandwidth
requirements and limitations

With the SIP Provider, agreed, no special hardware. Except is I want call recording, in which case I need a proxy along the way that's beefy enough.

Joe Terranova

PS: You probably also want to look at how you're monitoring 30 people.
At my office we use iSymphony. It's proprietary, it costs money, and
it's not very good, but it's the best we've seen. If you find better,
let me know:

Pretty colors. The boss will like :)

Thanks a lot for the long answer !


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