Advise needed migrating existing PBX to Asterisk

Hi,

One of my clients is using a Telrad 400 PBX with about 70 digital extensions and few other analog. Current Telrad has one PRI card for incoming calls.

Client ordered another PRI from another provider and want to route calls also via the new provider. Thing is that installing a new PRI card for the Telrad is about 2000$.

My client is planning to move to pure VoIP in the upcoming year so I think it won't be wise spending money on equipment that will be unneeded soon.

I guess I need PRI card on the Asterisk with atleast 3 channles (2 for incoming 1 for interconnecting the PBX's).

Can I decide later on the * server which PRI takes the call out?

Will I be able to register the current digital extensions on the Asterisk or should I just as time passes move more extension to IP?

My first goal is to get rid from the Telrad but users love the phone so much and extension with similiar capabilities cost alot.

Any help planning this project will be great - I have expreince with asterisk - never integrated old pbx though.

Thanks in advance

astervoice :

I guess I need PRI card on the Asterisk with atleast 3 channles (2 for incoming 1 for interconnecting the PBX's).

Those aren't channels you're talking about, it's ports. So you'd want 3 PRI ports. Each port can have a maximum of 30 [E1] or 24 [T1] channels.

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Can I decide later on the * server which PRI takes the call out?

Yes. This is known as a Man in the Middle installation. There should probably be an FAQ for this somewhere.

Actually have a read of this: http://www.voipuser.org/forum_topic_14989.html

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Will I be able to register the current digital extensions on the Asterisk

If the Telrad digital extensions aren't IP, then no, you will not be able to. However, so long as each extension has a DDI then you'll be able to call it from extensions registered on the Asterisk server. The DDI doesn't have to be a proper PSTN DDI of course, it just needs to work from the Telrad's PRI to the extension on the Telrad [ie there may be some programming work involved on the Telrad if each extension doesn't already have a DDI].

Quote:

or should I just as time passes move more extension to IP?

That's the beauty of a MitM upgrade, you can move people over gradually, or not move them over at all and just use Asterisk to do LCR, or use Asterisk to add IP to the Telrad. It's entirely up to you.

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My first goal is to get rid from the Telrad but users love the phone so much and extension with similiar capabilities cost alot.

If the Telrad works and your users like it, then you'll need to set some positive goals to sell it to your users. Let them see that they're going to be getting some new features [DISA, voicemail to email, softphone access, least cost routing, resilience], so that they can understand why they'll be having the inevitable teething troubles that come with any new system.