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New Member

IP Phone support on Router

Dear all,

Does anyone know how to calculate Router capacity to support IP Phone?

We are now running CallManager 4.2 on MCS7825. From document this can support up to 1000 IP Phone.

And we have R2851 with 3 E1 port and R2821 with 2 E1 port.

Currently we are using about 100 IP Phone and we'd like to add about 200 more.

Will the router able to support this amount of IP Phone? Do i need to add any other component?

Your help is much appreciate.

Best regards,

Cisco Employee

Re: IP Phone support on Router

look at the CME version you plan to use and you'll find how many phones you can have per platform

Cisco Unified CME and Cisco IOS Software Version Compatibility Matrix



if this helps, please rate



if this helps, please rate
New Member

Re: IP Phone support on Router

Dear Java,

But we're not using CME. We use call Manager on MCS7825 server. And the router running IOS: Cisco IOS Software, 2800 Software (C2800NM-SPSERVICESK9-M), Version 12.4(3h), RELEASE SOFTWARE (fc2).(c2800nm-spservicesk9-mz.124-3h.bin).

I afraid CallManager can support but Gateway Router can not support.


Re: IP Phone support on Router

For internal calls no router required but external calls it all depends on number of calls.

You should have idea as how many calls you cab handle on 3E1 and 2E1 ports.

You can check your router capacity for conferencing and other things by this.


Re: IP Phone support on Router

Because you have CallManager running on the server, the router only serves one primary purpose and that is as a voice gateway. As such, it doesn't matter how many phones on the network, but how many PSTN lines need to be supported. If you are not adding more PSTN lines, then the router will be fine.

Now, it sounds like you have a total of 5 E1 lines, so you are already supporting up to 155 voice channels. I certainly hope that is enough for you 100 users!!!

New Member

Re: IP Phone support on Router


Oh i see, for internal call it doesn't go through Router. So even if i add 200 IP Phone more for internal, it does not affect the router.

By the way, i don't have a cco account to login to use the calculation too. Is there any other way i can check it?

Thank you so much for your help.

Best regards,