So, I'm working on setting up a call center. Our outbound calls will be going to an off-site dialer so they'll be going over the internet as data (VoIP?). Then we have our customer service department, which will be, well, whatever they do...

My question is how do I segregate the two groups? We currently have COX Ultimate in (50D/5U), but I don't trust it. We're starting out with 24 outbound stations, but we want to grow it to 200-250, depending on what the building can fit. I just don't see that COX connection keeping up. So, I was planning on bringing in 3 T1s from XO and expand those as needed and just run the outbound traffic through them and all the remaning customer service traffic over COX.

This is the map I've come up with:

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I don't know if that right at all. Do we need to have an XO router for each T1? Can the T1s be plugged directly into the gateway? If so, how many connections should I have on the gateway assuming I want to expand? We currently have a SonicWall TZ100. Also, what kind of switches should I use? L1, L2, or L3?

I'd appreciate someone who knows networking and phones if you can take a look and tell me where I'm wrong. Cost isn't so much a concern right now, but try to keep it reasonable if you're going to suggest hardware.

Thanks in advance!


The simple answer is that your map will work: Your gateway router/firewall needs to know enough to send the "call center" traffic out to the XO T1's gateway as opposed to the Cox cable gateway, but that can be done with simple rules/static routes.
Regarding routers and other terminating hardware for the XO connection, that's between you and XO -- They should be handing off "something that looks like ethernet" for you to plug in to your gateway router/firewall.

The larger/more complex answer is that while what you've drawn works it's not an ideal situation: A failure of the XO links leaves you without voice connectivity ; A failure of the Cox connection kills your general data service.
You can work around that with some creative configuration work, but it may cause havoc with your call center's VOIP traffic (changing external IPs when you flip between Cox and XO, which will likely require some firewall fiddling at a minimum).

Since you're investing in the expense of T1s and telco-grade service contracts you may want to consider a pair of T3s (or a bunch of redundant T1s), possibly with your own BGP-announced prefix, either through multiple providers or through XO with redundant fiber paths to your premises and a nice tight SLA. The routers will handle failover and fault-tolerance (you can trust them pretty well), and since the external IPs won't be changing your firewall rules for the VOIP traffic can be nice and clean.
As a bonus this will give you an internet connection you can "trust" (to the extent that if it doesn't meet the SLA you can collect on penalties).

  • I see. Wouldn't the 3 T1s be redundant to each other? – Gup3rSuR4c Aug 30 '11 at 18:46
  • possibly -- for true redundancy you need different physical and logical paths (e.g. one T1 going out the north side of your building to provider A, and another going out the south side to provider B, and reasonable assurances that they don't physically run parallel to each other at any point lest they both be eaten by a backhoe) – voretaq7 Aug 30 '11 at 19:00
  • Also, looking at the Integra router we have in our other building (which is being switched to XO) it has 4 T1 ports on it, 1 PRI, 2 LAN. That looks sufficient to me for now, and if we have 3 T1s (maybe 4) wouldn't they be redundant to each other based on the router? – Gup3rSuR4c Aug 30 '11 at 19:07
  • Well, at this point we'll have to make due with what we have, which is probably just a single line coming into the building... The business being a start-up can't really afford to be bringing in new lines for thousands of dollars... – Gup3rSuR4c Aug 30 '11 at 19:09

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