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IP Telehony setup on 2900 Router.

I want to know whether is it possible to deploy voice setup in 5-10 branches with 2900 series router as a call manager present in a hub location and branches connected like spokes to it.

I m a bit confused about the subnet to be used on the IP Phones? IP phones should be in same subnet or different? How will the phones register on the call manager? And do I need PVDM card...?

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Cisco Employee

Re: IP Telehony setup on 2900 Router.

No you don't need to VPN in to get a remote phone to register.  You just want the phone top be routeable to the IP CME is running on.  If you wanted to, I suppose you can run CME on a public IP address, if you wanted, as long as you turn auto registration off.

The SPA 525 works with the UC500 platform and has VPN built into the phone if you wanted to go with that CME platform.  Otherwise, if you wanted VPN, you'd need a remote acces router doing VPN in front of the phone.

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Cisco Employee

Re: IP Telehony setup on 2900 Router.

When you say 2900 present *as* a Callmanager, I assume you are talking about Callmanager Express, which runs IP PBX software on the router itself.  Yes, you can do that on a 2900.

You could purchase a 2900 for every remote site, and trunk the CME routers to each other so they can call each other.

You could also put the CME at a HQ site and use VPN to register the phones at remote sites all to the same CME.  If you do this method, you will probably need DSPs (that's what a PVDM is) to have transcoders available in the CME router, since you'll likely want g729 across the WAN and Unity Express (voicemail) only does g711.  The DSPs will allow for those calls to be transcoded.

Other than for transcoding, you'll only need DSPs if you have POTS connections (PRI, analog FXO/analog FXS) to connect to an analog phone/fax or service provider.  If you just have IP phones and go with a SIP trunk for PSTN calls, you wouldn't need DSPs for those calls.

The subnet which IP phones are on doesn't matter.  They can be on whatever subnet you want to put them on.  The only thing you need to make sure is that theiur DHCP server has option 150 set for the CME IP, and that they have L4 connectivity to the CME IP from the network which they reside on.

Community Member

Re: IP Telehony setup on 2900 Router.

Hi Steven... thanks for the answer, my life just got easy Just wanted to know one thing if I want the CME at the HQ and IP phones at the remote sites should be able to register on the CME present at the HQ without using VPN.... is this possible?

As you said that the phones should have L4 reachability to the CME, is it ok that I configure static IP address on the phone and use OSPF on the routers and advertise the IP address of the ip phone with all zero wildcard mask.

I see that Cisco has phones for small businesses like SPA901

http://www.cisco.com/en/US/products/ps10034/

These small phones wont support VPN.... so just wanted to avoid the VPN

Cisco Employee

Re: IP Telehony setup on 2900 Router.

No you don't need to VPN in to get a remote phone to register.  You just want the phone top be routeable to the IP CME is running on.  If you wanted to, I suppose you can run CME on a public IP address, if you wanted, as long as you turn auto registration off.

The SPA 525 works with the UC500 platform and has VPN built into the phone if you wanted to go with that CME platform.  Otherwise, if you wanted VPN, you'd need a remote acces router doing VPN in front of the phone.

Community Member

Re: IP Telehony setup on 2900 Router.

2901 - 35 Phones
2911 - 50 Phones
2921 - 100 Phones
2951 - 150 Phones

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