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Max-Ephones Command Behavior in CUCME

The max-ephones command within CUCME has been upgraded as of CUCME version 4.3 (and later).  So, if you've had some experience with this command on some of the older CUCME versions, you will want to pay close attention to how this command works in the most recent release(s).  This translates to roughly IOS version 12.4(15)XZ and later.

Cisco Unified CME and Cisco IOS Compatibility Matrix

Download CME Software (requires CCO account and authorized contract)

Prior to the CUCME 4.3 Release

Prior to Cisco Unified CME 4.3, the max-ephones command specified both the maximum number of SCCP phones that can be registered AND configured.

What Changed?

In Cisco Unified CME 4.3 and later versions, the max-ephones command is enhanced to set the maximum number of SCCP phones that can register to Cisco Unified CME, without limiting the number that can be configured.

Also, the number of SCCP phones that can be configured is no longer limited to the maximum number that can be registered.  Also, it is not limited to the hardware platform.  This change expands the maximum number of phones that can be configured to 1000.

However, the maximum number of phones that can register to CUCME is still dependent on the number of phones supported by the hardware platform and is limited by the max-ephones command.

This enhancement supports features such as Extension Assigner that require you to configure more phones than can register. For example, if you set the max-ephones command to 40 and configure 80 ephones, only 40 phones can register to Cisco Unified CME, one at a time in random order. The remaining 40 phones cannot register and an error message displays for each rejected phone. This enhancement also allows you to assign ephone tags that match the extension number of the phone, for extensions up to 1000.  (Yes, I agree.  That would be a fun router config to deal with.)

What Happens If I Change Max-Ephones?

If you reduce the value of the max-ephones command, currently registered phones are not forced to unregister until a reboot. If the number of registered phones, however, is already equal to or more than the max-ephones value, no additional phones can register to Cisco Unified CME. If you increase the value of the max-ephones command, the previously rejected ephones are able to register immediately until the new limit is reached.

What is Extension Assigner?

Extension Assigner is a feature that gives installation techs the ability to assign extension numbers without needing administrative access to the Cisco Unified CME, typically during the installation of new phones or the replacement of broken phones. However, before the feature can be used, the system administrator must first configure Cisco Unified CME to allow specific extensions to be assigned. The system administrator must also provide the installation technician with the information necessary for assigning extension numbers to phones. The installation technician can then assign extension numbers to phones with access to only the phones themselves and with no further intervention from the administrator.

Extension Assigner Details

More Information
Cisco Unified Communications Manager Express System Guide

6 comments:

  1. what about max-ephone (sccp) and max-pool (sip) ,
    on a router like 2821 I can set both to 58
    does this mean I will be able to register 116 phones 1/2 on sccp and the other 1/2 on sip ?

    this lead me to another question , in the matrix compatibility , Maximum Total IP Phones = 50 but in reality I can set it up to 58 ??

    and finally what will be the behavior of restriction on a UC500 platform if we have a lic of 16 user , configureing 16 as SIP and 16 as sccp ?? will it accept both groups ?

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  2. @elhallak, re:UC500 licensing, I'm not familiar with this hardware - so, not sure if the licensing limit is enforced here. Anyone in the community know the answer to this?

    @elhallak, re:SCCP an SIP phone concurrent limits - I'd love to test this to be sure, but I don't have the environment to do so. Doing some research and will get back to you.

    The max-pool and max-ephone maximums are platform specific. So, these values will be capped depending on hardware.

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  3. From the compatibility matrix, "..maximum numbers of IP phones are for common Cisco Unified CME configurations only. Systems with large numbers of phones and complex configurations may not work on all platforms and can require additional memory or a higher performance platform."

    Also, "Total number of connected IP phones cannot exceed Maximum Total listed including SCCP and SIP phones on the same router."

    http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/requirements/guide/cme71spc.htm

    So, for a 2821 - it can have a maximum of 50 SIP, or 50 SCCP, up to a total mixed of 50.

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  4. well , this is my problem , I have seen this doc more than 100 times , info passed just in front of my nose
    thank you

    but I still did not get the 50 limit on the compatibility matrix , for the 2821 it says 50 but in the CLI I'm able to make max-ephone 58 ??

    Regards

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  5. From the compatibility matrix, "..maximum numbers of IP phones are for common Cisco Unified CME configurations only. Systems with large numbers of phones and complex configurations may not work on all platforms and can require additional memory or a higher performance platform." <-- this suggests that fewer than configured phones may be appropriate depending on the router configuration

    If you can define max-ephones to be more than 50, it may not be a hard limit. I've never load tested a CUCME to see how it behaves when you try to exceed 50 phones that are actually registered. <-- this suggests that more than the matrix can actually be configured (max-ephones)

    I'll do some more research and see what I can find - starting to seem that the matrix is really just a guideline, perhaps not enforced.

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  6. OK , I see what you mean , thank you

    ReplyDelete