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New Member

DNS environment for a Cisco VoIP shop?

Hi all...

Does a Cisco IP telephony implementation depend on DNS? Are there enterprises who have a successful Cisco VoIP implementation without it?

If not, what DNS implementations are supported?


Cisco Employee

Re: DNS environment for a Cisco VoIP shop?

>>depend on DNS?

Depends on what you are referring to. If you use hostnames instead of ip addresses of callmanager, then the phones will have to be able to resolve CCM hostnames.

If you do not need external name resolution for your CCM, such as going to the voice download page on, then the CCMs do not need it either.

If you are writing about Unity integration with Windows 2000 domain, then most definately you will need it.

H. M.

Re: DNS environment for a Cisco VoIP shop?

Callmanager and IP Phones definitely donot need a DNS for their operation, though its an option to use names instead of IP addresses. Unity requires that you integrate with Active Directory, which will require you to have DNS installed either on the local Unity machine or another Windows 2000 machine.

New Member

Re: DNS environment for a Cisco VoIP shop?

DNS is not necessary for Call Manager/Phones/Gateways. I always configure my systsems to use only IP Addresses, I don't want the phones to fail bacause of a DNS problem. However, if you decide to use DNS, any DNS server will do, it is a standard (the whole internet uses it). As mentioned above, unity will need DNS in the domain, but if you have a windows domain then that is already running anyway.

Re: DNS environment for a Cisco VoIP shop?

Be cautious with MGCP gateways. The hostname and domain name configured on the gateways is what is sent to CCM for the Domain Name under MGCP GW. If someone chnages a router hostname, domain name down the road down comes the calls.

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