Max number of Extensions in Hunt Group CUCM

[jejarosz1]

Hi all,

Can anyone tell me what the maximum number of extensions there can be in a cucm hunt group? I know its 32 for CME, wondering what it is for CUCM?

[Ratheesh Kumar]

Cisco recommends having a maximum of 35 directory numbers in a single line group configured to send the calls simultaneously to all DNs.
Additionally, the number of broadcast line groups depends on the BHCC. If there are multiple broadcast line groups in a Unified CM system, the number of maximum directory numbers in a line group must be less than 35. The number of busy hour call attempts (BHCA) for all the broadcast line groups should not exceed 35 calls set up per second.

Performance and Scalability
* A single Unified CM Cluster supports a maximum of 15,000 hunt list devices.
* A single Unified CM Subscriber supports a maximum of 100 hunt pilots with call queuing enabled per node.
* Hunt list devices may be a combination of 1500 hunt lists with ten IP phones in each hunt list, 750 hunt lists with twenty IP phones in each hunt list, or similar combinations
[https://www.cisco.com/c/dam/en/us/td/i/templates/note.gif]Note

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When using the broadcast algorithm for call coverage, the number of hunt list devices is limited by the number of busy hour call attempts (BHCA). Note that a BHCA of 10 on a hunt pilot pointing to a hunt list or hunt group containing 10 phones and using the broadcast algorithm is equivalent to 10 phones with a BHCA of 10.
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* The maximum number of simultaneous callers in queue for each hunt pilot that you can configure ranges from 1-100 (default 32).
* The maximum wait time in queue for each hunt pilot that you can configure ranges from 0-3600 seconds (default 900).
* An increase in the number of hunt lists can require you to increase the dial plan initialization timer that is specified in the Unified CM service parameters. Cisco recommends you to set the dial plan initialization timer to 600 seconds if you have 1500 hunt lists configured.
* Cisco recommends having no more than 35 directory numbers for a single line group when using broadcast algorithms with call queuing. Additionally, the number of broadcast line groups depends on the busy hour call completions (BHCC). If there are multiple broadcast line groups in a Unified CM system, the number of maximum directory numbers in a line group must be less than 35. The number of busy hour call attempts (BHCA) for all the broadcast line groups should not exceed 35 calls set up per second.

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/10_0_1/ccmfeat/CUCM_BK_F3AC1C0F_00_cucm-features-services-guide-100/CUCM_BK_F3AC1C0F_00_cucm-features-services-guide-100_chapter_01000.html




Hope this Helps
Cheers
Rath!

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[jejarosz1]

Hi Rath, thank you for the detailed response. I’m coming at it from a cme knowledge perspective. Right now I can have up to 32 extensions in a hunt group. I have them setup as a parallel ring. What would the comparable be in cucm?

[Ratheesh Kumar]

Hi there
The distribution algorithm in CUCM for Hunt Group is as follows. For parallel ring you should select Broadcast


Distribution Algorithm


Choose a distribution algorithm, which applies at the line-group level, from the options in the drop-down list box:

*Top Down-If you choose this distribution algorithm, Cisco Unified CM distributes a call to idle or available members starting from the first idle or available member of a line group to the last idle or available member.

*Circular-If you choose this distribution algorithm, Cisco Unified CM distributes a call to idle or available members starting from the (n+1)th member of a route group, where the nth member is the next sequential member in the list who is either idle or busy but not "down." If the nth member is the last member of a route group, Cisco Unified CM distributes a call starting from the top of the route group.

*Longest Idle Time-If you choose this distribution algorithm, Cisco Unified CM only distributes a call to idle members, starting from the longest idle member to the least idle member of a line group.

*Broadcast-If you choose this distribution algorithm, Cisco Unified CM distributes a call to all idle or available members of a line group simultaneously. See the Note in the description of the Selected DN/Route Partition<> field for additional limitations in using the Broadcast distribution algorithm.

The default value specifies Longest Idle Time.




Hope this Helps
Cheers
Rath!

***Please rate helpful posts***

[jejarosz1]

could I have more than 32 phones in the hunt group?

[Ratheesh Kumar]

Yes, The maximum of 35 directory numbers in a single line group is Cisco recommendation.

Also the number of broadcast line groups depends on the BHCC. If there are multiple broadcast line groups in a Unified CM system, the number of maximum directory numbers in a line group must be less than 35. The number of busy hour call attempts (BHCA) for all the broadcast line groups should not exceed 35 calls set up per second.

hope this helps

Cheers

Rath!

***Please rate helpful posts***