CUCM - number of users able to join one conference call

Met44

I am attempting to figure out how many users would theoretically be able to join one large conference call, from a processing perspective, with the Call Manager mixing calls in software (not using a DSP). I would be assuming something around a 2GHz processor, and also assuming that no transcoding is taking place, and I am ignoring for this time the idea that "phone discipline" may limit the usefulness of such a potentially large conference call. Simply thinking about mixing the audio streams and sending them out. I will be doing my own calculations for Asterisk in the next few months, and will be curious to compare them.

Would appreciate it if anyone has information to share on this, or have links that discuss the processing requirements of Cisco Call Manager to mix calls for conferencing.

mikej412

Cisco CallManager System Guide, Release 4.1(3) - Conference Bridges [Cisco Unified Communications Manager (CallManager)] - Cisco Systems

Cisco Conference Bridge Software CallManager 4.1(3)

Software conference devices support G.711 codecs by default.
The maximum number of audio streams for this type equals 128. With 128 streams, a software conference media resource can handle 128 users in a single conference, or the software conference media resource can handle up to 42 conferencing resources with three users per conference.
If the Cisco IP Voice Media Streaming Application service runs on a different server than the Cisco CallManager service, a software conference cannot exceed the maximum limit of 128 participants.



Caution If the Cisco IP Voice Media Streaming Application service runs on the same server as the Cisco CallManager service, a software conference should not exceed the maximum limit of 48 participants.

7.0(1) is the same
Cisco Unified Communications Manager System Guide, Release 7.0(1) - Conference Bridges [Cisco Unified Communications Manager (CallManager)] - Cisco Systems