July 15, 2024


Sapiens Digital

Cisco CCNA Voice Certification Exam Tutorial – Default Max Ephone and Ephone-dn and Configurations

2 min read

How many phones and directory numbers can be configured on Cisco Unified Communications Manager Express by default?

Answer: Zero!

Yes, by default, no ephones or directory numbers can register. Before doing anything else, the following configuration is required:


Router#configure terminal
Router(config-telephony)#max-ephones 4
Router(config-telephony)#max-dn 8

This allow up to 4 phones to register / be configured and 8 directory numbers.

If you don’t do this, the router will not allow ephones or ephone-dns to be created. Here is an example of what would happen:

R1(config)#ephone 1
ephone tag 1 exceeds max-ephones 0
R1(config)#ephone-dn 1
dn 1 exceeds max-dn 0

The maximum number of ephones and ephone-dns that can be configured is platform dependent. Here is an example of my router that can support 30 phones with up to 150 ephone-dns:

R1(config-telephony)#max-ephones ?

Maximum phones to support

R1(config-telephony)#max-dn ?

Maximum directory numbers supported

Cisco have a great document showing you how many ephones/dns are supported on specific platforms. Have a look here

As an example, using CME version 4.3:
The 2801 supports 25 phones and 120 ephone-dns
The 2811 supports 35 phones and 144 ephone-dns
The 2821 supports 50 phones and 192 ephone-dns
The 3845 supports 250 phones and 720 ephone-dns

(There are others, please refer to the link above for a full list)

Cisco also recommend that you only enable the number of ephones and ephone-dns for the number you require, not the maximum the platform can support. The reason is that when a ephone / ephone-dn is created, it uses up memory on the router. Don’t just create them because you can! Create only what is required.

To your success!

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