Anyone using comcast business for 3-5 lines?

If you have the ability to get FiOS I would do that instead. That being said if you go by the lowest advertised numbers (the upload numbers or 5 and 10) you get the following simultaneous calls assuming an uncompressed voice codec and SIP signaling (generously estimating 90kbps per call with packetization overhead (uncompressed codecs are 64kbps)):

5120 (5 mbps) / 90 (90 kbps) = 56.8 simultaneous calls. (I would call it 50 to be safe)

10240 (10 mbps) / 90 (90 kbps) = 113.7 simultaneous calls. (I would call is 100 to be safe)

That is assuming they actually provide those numbers. Most likely you'll see lower numbers but based on your requirements I think you'll be OK.

My experience, however YMMV:

I have a bunch of customers using SIP trunks over Comcast modems just north of you in Southern NH. Generally speaking they end up with dedicated service just for voip, and another dedicated service just for other Internet use. Is this necesary? Maybe not, but it adds some comfort level and you never worry about Internet or VPN users dragging down the voice. The older 6/1 DOCSIS 2.0 service for $60/month has been very reliable. Most of these customers are frequently hanging around the 6 concurrent call area over this service, and they think PRI features like DID's and callerid are great.

The 22/5 service on a DOC 2 gateway will pretty much always give you very close to 22/5.

The 22/5 service on a DOC 3 gateway is pretty consistently providing 60/9.5 in my area (when it works). However, these DOC 3 business gateways seem to be a bit problematic. When they work, they work well, but they are sometimes flaky. I've spent a LOT of time chasing down packet loss, etc, that ultimately ends up with rebooting the modems to resolve the issue. Once a year is fine, but twice a week gets old quick. (Several customers, different nodes.) Comcast business tech support is pretty much useless. They tell me the service is working fine when it doesn't pass any traffic and they are unable to ping the modem, so getting help from them with intermittant problems is damn near impossible.

Unrelated to trixbox, if you do go with Comcast service, my experience has been that you'll definately want to verify the service tier that has been provisioned. About 25% (my own experience) of the time they bill for higher tiers, but don't get the modem pulling the correct tftp file and you are provisioned for a lower tier. Often takes hours on the phone to get the tech to understand the issue, and get it resolved. I could write books about the fun (translation=time I've lost) with Comcast installs. Unfortunately, they are often the best option in my area.

Thanks everybody! Verizon says no FiOS at this address (middle of the Back Bay) so the Comcast service is the best I can get unless I spend megabucks. I'll be getting their service regardless and will probably give Trixbox another try.

Roger, how do you know whether you're getting DOCSIS 2, 3 etc.? Is that something I have any control over, or is it just a roll of the dice? And what do you use to qualify the service tier provisioned?

How to tell DOCSIS 2 or 3: Assuming 3.0 is available in your area (I assume it is in the Back Bay and everywhere else in the city), you can ask the sales rep when you order which tiers are which. Also, google the gateway model number that they install. The installers for some reason seem to have flexibility about which gateway they install.

If you log into the gateway (installer should leave you instructions and username/pwd), you may see multiple channels "locked" or bonded together. If that is the case, it is 3.0 as 2.0 doesn't have this ability.

You cant test your ul and dl bandwidth using http://speedtest.comcast.net, and be persistent if you are not getting very close to what you are suppose to be getting.

We have a 4 site configuration - 1 "main"...three branch sites. Recently, one of the branch offices was relocated. The main site has a data T1, the branch offices have Comcast - probably 16/2 - but I'm not 100% positive. Since the relocation - we're having voice problems in the relocated office - calls degrade, and ultimately drop. As a test - we allowed (temporarily) public access to the box in the main site, and bypassed the VPN to register two of the phones. The calls on those two phones degrade as well - but - they tend to not drop out completely. We cannot get Comcast to take the issue seriously...but I am very convinced it's them. They claim to have replaced the modem - for what that's worth - but - all of the equipment was working just fine when it was 5 miles down the road.

Anyway - I've tried - in vain - to get to "tier 2" support - because the people at Tier one have no idea what I'm talking about when I ask about QoS, etc...just getting a static IP address on the DOCSIS modem was an project in and of itself.

I know at least a basic level user ID to login to their equipment - what can I tell / show them to get them to take the issue seriously? I'm sure that the bandwidth is dropping out - probably to nearly nothing - and then recovering in a few seconds - but - it's long enough for the phones to lose the calls...any advice will be GREATLY appreciated!

David

Have been using Comcast with a good SIP provider and 8 call paths the past 2 years. The first year we had Comcast and Qwest for a backup. Pulled Qwest out a year ago. Now it has not been perfect but I would say Comcast has been down maybe a 1/2hour per year and that might be padding it a little.

I do think keeping the phone completly seperate is a great idea and I agree with that. But we are cheap and have been just using the Comcast Connection with a little RVO2 router to give dedicated bandwith the TB. We are an engineering company and burn up are fair amount of bandwith with nice big CAD files.

One thing I noticed over the last few years is that we rarley get a fax and even the number of calls have gone down. Just about everthing is done with email at least in my little world. So I can understand you thinking if its as good as a cell phone thats good enough.

My next step is to toss a card in the TB so I can use the fax PSTN line for a back up. We also have a second SIP provider as a back up to. We have used the second backup SIP provider more than we used the second internet conection I do belive.

Good Luck

Jay