Need Advice on New VOIP setup for small office


#1

I’m helping a friend open a small office of 12 people. They will be heavy voice & fax users.

Here’s the situation:

1 main local number
12 total extensions

  • 6 local DID included in the 12 extensions above

I’m looking at spec’ing the Internet connection currently. I’m wondering what questions I need to ask the provider… QOS, Latency, Packet Loss, etc.

I want the voice quality to be very near POTS lines. I will be using GigE with QOS on the LAN and can restrict the port bandwidth at the firewall to ensure VOIP traffic gets priority.

What would my required internet connection bandwidth be if all 12 lines were in use at one time and I still wanted to allow decent browsing speeds?

I’m also not sure of the VOIP provider to use, suggestions are appreciated!
Any advise is highly appreciated!


#2

I would like to track this topic

Rich


#3

There are things you can do to minimize bandwidth such as using G729 and what not but I think a solid business solution should be able to handle the worst case of G711 for all 12 lines. That is 64k each x 12 lines +overhead=768000Kb/s each way+overhead.

The overhead is a bit harder to determine. Say 50% overhead for TCP/IP protocol, WAN/Internet instantaneous (realtime) congestion etc. + 1.5Mb/s down for internet/email etc… That would put you up to about 2.5Mb/s downstream which is easy enough. The problem will be the upstream bandwidth. You would need a consistent 1Mb/s minimum. 1.5Mb/s would be advisable.

My 2 cents


#4

Thanks mustardman

Much appreciated


#5

you can calculate it for yourself here:

asteriskguru.com/tools/bandw … ulator.php

I could recommend to take a separate internet connection for the voip, or divide the line in two pipes, actual variable shaping for the voip will cause big headaches and might not work if phones dont do QoS tagging.


#6

Cool calculator!

Zoa,
I’m not sure what your saying regarding QoS and separate networks. For phoning out on the internet/WAN like this a good quality router that can prioritize SIP is essential IMHO. That is probably one of the things your getting at right? Whether that is done with QoS tags or VLAN probably does not make much difference at the packet level. Which ever is easiest to configure I supposes.

A separate physical network kind of defeats one of the main benefits of VoIP which is to use or reuse the existing IP network. That will probably be the less expensive way to go as well.


#7

Most of the time its cheaper to take two connections, than to buy a fancy router and hire a consultant to do the shaping.

Besides that, surfing will be slow if he uses the voip :smile:


#8

[quote=“zoa”]Most of the time its cheaper to take two connections, than to buy a fancy router and hire a consultant to do the shaping.

Besides that, surfing will be slow if he uses the voip :smile:[/quote]

If your talking separate physical network that is separate wiring, separate switches, separate router. Might as well just buy a traditional phone system which already does than very well.

IMHO, 1 good network with good quality components is better than 2 cheap networks.


#9

i think zoa was talking about having a 2nd 'net connection/router on the same network, and setting the gateway for the * server to that. makes a lot of sense if you have the budget for it or it means you can reduce your PSTN lines by using VoIP.


#10

Ah so. Ok, that makes more sense. VoIP router could be on same subnet and only * would use it. I never thought about doing it that way before. Interesting idea.


#11

Here’s my current thought on what I may do for the setup…

buy two switches: one for servers/workstations, one for IP phones. This way there is no need for QoS on the switches.

get a full T1 and split it with 768k for voice and the remaining for data.

Now a decision I need to make is to I use the local carrier for my phone numbers or use an Internet carrier like BroadVoice… any thoughts or experiences you all can share?


#12

My $0.02 on BroadVoice et al for business: nobody I’ve evaluated is really geared towards business, at this point. Most offer some sort of business package, but the real business features aren’t there. With BV, I had to set up individual accounts for each DID I wanted; the available numbers were very jumbled, getting a block of 20 numbers is out of the question. Going with other providers, I couldn’t get the good LD packages that BV and the bigger boys are offering, and I even had one provider tell me that it would take at least two weeks to provision a single number. I can get a PRI with LD for $0.0189/minute - some of these VoIP guys are charging well over $0.02. When you’re looking at 50,000 minutes or more a month, that really makes a difference, especially when the quality doesn’t consistantly meet the level of PSTN.

Broadvoice, in my experience, is the best - but for business calls, I found the service level to be less than acceptable; this isn’t necessarily BV’s (or any other VoIP/PSTN gateway’s fault) - the Internet is simply unreliable for voice, from a business perspective. You might have 30ms to your provider for one call, and >300ms on the next call. It’s the nature of the beast.

For your situation, may be better off sticking with a TDM400 or two talking to POTS - have your CLEC or Baby Bell set up a hunt group on your POTS lines (MCI does this at no extra charge for a business account) and let * do the rest.


#13

[quote=“bsdbigot”]
For your situation, may be better off sticking with a TDM400 or two talking to POTS - have your CLEC or Baby Bell set up a hunt group on your POTS lines (MCI does this at no extra charge for a business account) and let * do the rest.[/quote]

This is good advice and I HIGHLY appreciate it! I was leaning towards this solution just to ensure quality of service.

one question… what is a hunt group?


#14

Let’s say you have 6 DID’s, one of which is the main number. You could put three of these DID’s, including the main number, into a hunt group, which is kind of like setting Call Forward Busy, depending on the type of hunt. So, if you have more than one concurrent inbound call, your customers won’t get a busy signal (unless all three lines are filled)


#15

gottcha!