The Cisco Hardware Conference Bridge supports the Cisco Catalyst 4000 and 6000 Voice Gateway Modules and these numbers of conference sessions:
On the Cisco Catalyst 6000:
In a G.711 conference, there are 32 available streams; up to 10 conference sessions with three participants in each conference or one conference session with 32 participants.
On the Cisco Catalyst 4000:
In a G.711 conference, only 24 conference participants are allowed; a maximum of four conferences with six participants each.
For the Cisco Software Conference Bridge, the maximum number of audio streams is 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.
Note: 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 must not exceed the maximum limit of 48 participants.