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Multiple T-1's from different carriers

I have a client that is in a building that has managed telephone services. The building has a call manager and 10 T-1's for call traffic. Currently, 6 T-1's are being used for outbound and 4 T-1's are being used for inbound traffic. The 6/4 T-1's are from different providers (i.e. the 6 outbound are from one company and the 4 inbound from another provider).

The questions I have are as follows:

  1. Why would you want to separate inbound and outbound traffic like that?

  1. Can't you use either of the T-1's for both inbound and outbound traffic?

  2. What would happen if all of the inbound (or outbound T-1's for that matter) went down? Can the other T-1's take over as a failsafe? What is required for that?

  1. If a failure does occur how do the DID's know where to go? Aren't the DID's down since the T-1 is down?

  2. What can be done to insure uptime and create a failsafe so that phone service does not go down inbound or outbound?

Thank you all in advance.

Paul

Reply to
PaulJCohen2007
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Paul,

First, it appears that by saying T1, you mean PRI. Yes, a PRI is a T1, but there is a technical difference when comparing with a data T1, as the PRI will include voice services. So, given that assumption, I'll do my best to answer your questions. I'm used to a smaller number of PRI's and gateways for a location, but still have the concepts down.

  1. This would be done to keep one type of call from overwhelming the other. For example, you could be be overwhelmed with incoming calls (denial of service or some other issue) and this would prevent you from making outgoing calls. By separating them, you insure that each has a certain amount of time slots available.

  1. Potentially. This is easier if all lines are from the same carrier. Outgoing is fairly simple to share the extra lines, but incoming is a little more difficult, since the range of DID's would be different. One carrier would not know to reroute all calls to another carrier on failure. You could have them manually forward the calls for all incoming DID's, but for a network of this size, that would probably be a nightmare. And, then you'd have to have them turn off forwarding once service is restored. Also, keep in mind for the outgoing calls that some carriers will not allow you to send an outgoing Calling Number that does not match the DID's you are assigned, at least without a special assembly for doing so.

  2. Bummer !!!! This could happen if there is a cable cut. However, I would hope that if you are receiving this number of lines, that you have requested services from different CO's and different paths to minimize the chances of this. I addressed the failover in number 2.

  1. Yep, the DID's go down with the lines (group of lines from the telco, not any individual PRI). So, if ALL incoming PRI's are down, then the DID's are down. But, hopefully, with good planning, you won't lose all at any given time and you can make do with the minimal number. You should over provision to the amount that is critical to your business.

  2. Over provisioning is a start as mentioned in #4. But, also, redundancy as mentioned in #3. Lastly, you can actually have the PRI's come into completely different facilities. This way, even if there is a major cable cut, you probably won't lose everything.

There are ways to build redundancy into your phone network, but they often come with a cost. It comes down to how critical it is to your network and what your budget is. It is hard to say without the bigger picture if this is a good design, or not. I do hope that they have a second call manager, though - that would be a must for this design.

Hope that helps,

Jim

Reply to
Scooby

Could be a bunch of reasons. It could be a low-cost method of redundancy, if one carrier goes down, at least you have the other functionality, etc. Could be cost savings to be able to make outbound over another carrier that charges more for inbound DIDs than the first one.

Depends on the carrier and the type of circuits. For instance, many old-school ILECs on a CAS T1 doing DIDs can only do inbound calls on the CAS channels set asside for DIDs. They don't support outbound calls on the CID channels.

Not really split across carriers like that. You can buy that level of service from a single carrier, but its going to cost money. But when its split across carriers, they aren't going to allow dynamic updates to the call-routing databases.

Yes, unless you get some high-end call-routable services from a single bigger carrier. Ie. call-centers for the big companies can route their DIDs from one call-center to another on a schedule, or a web-page control of where the DIDs route.

Ask your carrier what they can do, and how much it'll cost.

Reply to
Doug McIntyre

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