Joe Terranova on 3 Jun 2011 15:09:27 -0700

[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

Re: [PLUG] VoIP setup

> 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.

I'm guessing you only really need one phone number? If you want with
someone like, 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.

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' 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

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

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:
Philadelphia Linux Users Group         --
Announcements -
General Discussion  --