I have a few basic queries :
What is the maximum number of phones we can have with CUCM 4x cluster ?
What is the maximum number of phones we can have with CUCM 6x cluster ?
What is the maximum number of phones we can have with per MCS 7835, 7845 ? Does the limit here depend on the CUCM version ?
Can we have 2 POTS dial-peers configured on a single port ?
The max number of phones is not based on version. It is based on platform (e.g. MCS 7835, MCS 7845, etc.). The capacity numbers for "max phones" is the same for 4x/6x/7x. They are:
But that isn't the whole story. There are more variables one should consider when choosing a platform or determining the size of a CUCM cluster. I won't go into all of that on this thread. But I will point you to some documents you should look into:
The details on the capacity limits for servers is in the "Unified CM Platform Capacity Planning" chapter of each of the above documents. I also recommend reading through the entire SRND for the version that you have deployed.
In regards to POTS dial-peers, the answer is yes you can have multiple dial-peers that point to the same physical port.
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