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Design Guidlines H.323

I have the following questions about the Cisco IP Telephony Design Guide:


In "Table 3-1 Cisco Callmanager Cluster Guidelines" there is a column "Maximum Number of IP Phones per Cisco CallManager ". What is included in the term IP Phones? Is it only hard phones or does it also include soft phones conference bridges and transcoders? For example can you have 2500 IP hard phones and 2500/20=125 soft phones for a max of 5000 units.


In "Table 3-2: Weights by Device Type" we have no weights for H.323 hard phones and H.323 Soft phones. What is the design guideline for these devices?


Re: Design Guidlines H.323

I’m sure IP Phones includes any hard phones or does it also include soft phones conference bridges and transcoders as well as any other IP telephony devices that come out in the future. I’m sure that document was written before many of these things came about. Couldn’t hurt to run your design by your Cisco design engineer.

New Member

Re: Design Guidlines H.323

Hello Pieter,

TAPI is Microsoft’s Telephony Application Program Interface. It is a C++ utility that requires Cisco’s TSP (TAPI Service Provider) to run. It is my understanding that it does count as 20 devices (not phones).

A phone is a hard IP Phone and counts as one phone and one device. A TAPI connection counts as 20 devices and zero phones.

The chart that you are looking at is old and has not been modified for the increase in processor speed when Cisco released the MCS7835-1000.