The Meet-Me Conference uses the Media Resource Group assigned on the Cisco CallManager. In this Media Resource Group, a Cisco Conference Bridge must be configured in order to handle the Meet-Me Conference. You can choose to use the Cisco CallManager Software Conference Bridge, with the use of the actual Cisco CallManager Server, or the Cisco CallManager Hardware Conference Bridge, which is used as a Catalyst 6000/6500 WS-X6608 Port.
The Cisco CallManager Software Conference Bridge supports only G.711 a-law and G.711 u-law and does not understand any other codec such as G.729. External callers cannot be added to the conference if they use a codec other than G.711. In order for calls that originate as G.729 to be connected with phones that use G.711, a transcoder is used.
The Cisco CallManager Hardware Conference Bridge devices provide transcoding for G.711, G.729, G.723, Gobal System for Mobile Communication (GSM) Full Rate (FR), and GSM Enhanced Full Rate (EFR) codecs.
You can select the maximum number of participants allowed in a single Unicast Meet-Me Conference. This value depends on the capabilities of the software/hardware conference bridge; for example, a Cisco CallManager Software Conference Bridge conferences a maximum of 128 participants. This amount of participants can cause performance degradation on a Cisco CallManager that runs on the same server. If you need that many participants at the same time, install the Cisco IP Voice Media Streaming Application on a separate server. The default number of participants Cisco CallManager specifies is 48.
Caution: Although a single Cisco CallManager Software Conference Bridge device can run on the same server as the Cisco CallManager service, Cisco strongly recommends against this configuration. If a conference device runs on the same server as the Cisco CallManager, the service can adversely affect performance on the Cisco CallManager. This issue occurs when all the participants are logged in to the Meet-Me Conference and you have a high telephony rate usage. The warning is given in order to understand that the Meet-Me Conference requires CPU resources as well as the Cisco CallManager service. If you don't have such a highly demanding usage of your telephones, all in use at the same time, there are no problems with the Meet-Me Conference feature.