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Large site with SRST, no IP PBX

Imagine I have a site with 1800 IP phone users. This is a centralized design and CUCM is in the data center, connected via MPLS.

I know typically we would place a CUCM subscriber in the branch and a gateway connected to PRI in case the MPLS circuit/SIP trunking goes down.

But company wants to experiment as much as possible with private cloud solutions and therefore attempt is to fulfill all IP Phone requirements without a CUCM onsite.


Let's say I place two 3945E in the branch to handle SRST so that I can provide SRST for 1800 IP Phone users.

Let's say the MPLS circuit goes down.

How can users within the branch call each other? Can I accomplish users calling inside the branch with SRST or do I need Comm Manager Express?

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Large site with SRST, no IP PBX


You do not need CME. It will work with SRST also.

Divide the branch in two parts. Half of the IP phone will regester to one 3945 and another half to second 3945. Now we just have to add dial peers to call beterrn these phones in both the routers. You will have to make sure that you divide the phones in such a way that you will not have any overlapping in dialpeers.


Ronak patel

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Large site with SRST, no IP PBX

You can also configure dial peers and translation patterns so your voicemail pilot will call out to a DID and directly into your voicemail server (assuming the voicemail server has a DID setup for outside accesss).

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