Media resource is software or hardware based entity that performs media processing functions on the data stream to which it is connected.
In Cisco Unified Communication Manager IP VMS [IP Voice Multimedia Streaming Service] is used to provide software based media resources. Digital signal processors are used to provide both hardware and software based media resources.
Conference Bridge [CFB]
Conference Bridge mix the audio streams from all the participants in the conference.It collects the audio from all participants but doesn't send back to the originating device.
CFB is both in hardware and software based media resources.
If all the participants in the conference are using G.711 mu-law then software based media resources are used.
If all participants use a codec other than G.711 mu-law then hardware based media resources are used.
Media Termination Point [MTP]
Media Termination Point is an entity that bridge two full duplex media stream together and allow them to set up and tear down independently.
It is used for transcoding from G.711 mu-law to G.711 a-law and vice versa.
CFB is both in hardware and software based media resources.
A software MTP supports only G.711 streams or passthrough mode in the codec.
A hardware MTP is used to bridge two connections which utilized different packetization period.
Annunciator
An annunciator is a software based media resource which provides the ability to stream messages or call processing tones from system to user.It uses SCCP messages to establish one-way RTP streams.
For most SIP devices call processing tones are downloaded at the time of registration.
To establish two-way media connection with an annunciator enable/true Duplex Streaming in CUCM service parameter.
An annunciator is capable of supporting G.711 a-law, G.711 mu-law, G.729, Cisco wideband codecs without transcoding.
It is automatically created when IP VMS service is activated in CUCM.
It registers with the single CUCM at a time as defined by its device pool and CM group.
An annunciator supports 48 simultaneous streams if it is running on the same server with the CM services.
Music On Hold [MoH]
MoH is a software based media resource which provides one-way music stream to the user which is put on hold.MoH server must share the following information with the CM cluster through the DB replication process.
- Audio source
- Unicast or Multicast
- Multicast Address
It is required to enable IP VMS service on all CM nodes to configure MoH server.
CUCM supports unicast and multicast MoH transport mechanism.
Unicast MoH
It is a point -to point one-way audio stream between MoH server to end points.Unicast MoH create a separate stream for each user/endpoint.
Unicast MoH call flow is initiated by a message from Unified CM to MoH server.
Multicast MoH
It is a point-to-multipoint one-way RTP stream between MoH server and multicast group IP address.The endpoints requesting MoH can join a group as needed.
Multicast MoH is initiated by a message from Unified CM to a holdee device. This message instruct device to join the multicast group address of the configured MoH audio stream.
Type of Hold
Two types of Holds are there.
- User Hold - User hold at IP phone or at PSTN
- Network hold- Network hold can be occurred from Call Park, Call Transfer, Conference or Application based hold
Holder and Holdee
The basic process of MoH in CUCM consist of two components, they are holder and holdee.Holder is end point user or device which place a call on hold. Holdee is end point user or device which is placed on hold.
