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Describe and Configure Music on Hold

In this lesson CCNA voice exam we will learn on how to configure Music on Hold in Cisco Unified CME. No voice network is complete without having music coming out of handsets of phones while holding the line. Cisco unified CME has the capability to stream Music on Hold (MOH) from a WAV or AU audio files which we copy to the flash memory of the router. CME has the capability to stream audio either in multiple unicast streams (more resources intensive) or as a single multicast stream (less resources intensive but needs a multicast configuration of network). CME can also stream MOH using G.711 or G.729 codecs.

Internal callers (making calls between extensions in the same Cisco unified CME) hear music when they are on hold or line being transferred. The multicast moh command is used to enable flow of packets to the subset on which the phones are located. Internal extensions that are connected through an analog voice gateway or via WAN (remote extensions) don’t hear Moh on internal calls.

We can disable multicast MOH per phone using the no-multicast-moh command in ephone or ephone template configuration mode.

G.729 codec was designed for human voice, so the quality of MOH is lower as compared to MOH streamed with G.711. Also CME will use transcoding DSP resources to convert the MOH to G.729 codec. So it is highly recommended to use G.711.

MOH is an audio stream that is played to PSTN and VoIP G.711 or G.729 callers who are placed on hold by phones in a Cisco Unified CME system. This audio stream is intended to reassure callers that they are still connected to their calls.

When the phone receiving MOH is element of a system which use a G.729 codec, transcoding is needed between G.711 and G.729. The G.711 MOH will be translated to G.729.

The audio stream that is used for MOH could be from two sources:

Audio file—A MOH audio stream from an audio file is supplied from an .au or .wav file held in router flash memory. We will learn how to configure an MOH audio stream from an audio file.

Live feed—A MOH audio stream from a live feed is supplied from a standard line-level audio connection that is directly connected to the router through an FXO or "ear and mouth" (E&M) analog voice port.

Let’s see now how to configure CME router to support multicast MOH, streaming music from a flash file called bonjovi.wav.

CME_voice (config) # telephony-service

CME_voice (config-telephony) # moh?

Word music on-hold filename containing G.711 A-law or U-law 8 kHz encoded audio file (.wav or .au format). The file needs to be loaded in flash memory of router.

CME_voice (config-telephony) # moh bonjovi.wav

CME_voice (config-telephony) # multicast moh?

A.B.C.D define music-on-hold IP multicast address from flash

CME_voice (config-telephony) # multicast moh 239.1.1.55?

Port define media port for multicast moh

CME_voice (config-telephony) # multicast moh 239.1.1.55 port?

<2000-65535> specify the RTP port: 2000 – 65535

CME_voice (config-telephony) # multicast moh 239.1.1.55 2123

Music on Hold from a Live Feed

The live-feed feature is used to connect to a CD jukebox player. To configure MOH from live feed we need to setup a voice port and dial peer from the call and create a dummy ephone-dn. The ephone-dn will be assigned a phone and extension number to make/ receive calls, but the number is never associated to a physical phone. Only one live MOH feed is support per system.

Use of an analog E&M port for live-feed MOH interface requires minimum number of external components. We can connect a line-level audio feed (standard audio jack) directly to pins 3 and 6 of an E&M RJ-45 connector. The E&M voice interface card (VIC) has a built-in audio transformer to provide proper electrical isolation for the external audio source. An audio connection on an E&M port does not require loop-current. The signal immediate and auto-cut-through commands disable E&M signaling on this voice port. A G.711 audio packet stream is generated by a digital signal processor (DSP) on the E&M port.

In case you are using an FXO port as interface for live-feed MOH, connect the MOH source to the FXO port using a MOD-SC cable if the MOH source has a different connector than the FXO RJ-11 connector. MOH from a live feed is supported on the VIC2-2FXO, VIC2-4FXO, EM-HDA-3FXS/4FXO, EM-HDA-6FXO, and EM2-HDA-4FXO.

We can directly connect the live-feed source to an FXO port provided the signal loop-start live feed command is configured on the voice port, or port is connected through an external 3rd party adapter for battery feed. External adapter must supply normal telephony company battery voltage and correct polarity to the tip/ring leads on FXO port and transformer based isolation on external audio source and tip/ring leads of the FXO port.

Music from a live feed is a continuous stream into MOH playout buffer instead of being read from a flash file, which leads to 2 seconds delay. An outbound call to a MOH live-feed source is attempted (or reattempted) every 30 seconds until the connection is made by the directory number that has been configured for MOH. In case live-feed source is unavailable, the flash memory source will be automatically activated.

A live-feed MOH connection is created as an automatically connected voice call made by Cisco unified CME MOH system or using an external source by directly calling in to live-feed MOH port. An MOH call can be from / to the PSTN or can precede via VoIP with voice activity detection (VAD) disabled. It is presumed to be an incoming call unless the optional out-call keyword is used while configuring moh.

The Cisco Unified CME router uses the audio stream from the call as the source for the MOH stream, discarding any audio stream from flash file. One such example an example of an MOH stream received over an incoming call is an external H.323-based server device that calls the ephone-dn to deliver an audio stream to the Cisco Unified CME router.

We will see now how to configure music on hold from a live feed:

When we configure MOH from an audio file and live feed both, the router first locates the live feed. In case live feed is configured it does not use audio source file. In case live feed in not found or fails due to any reason, router uses audio file as secondary source. We cannot use FXS port for live feed.

We will enable MOH from an outgoing call on voice port1/1/0 and dial peer 7777.

Voice-port 1/1/0

Auto-cut-through

Operation 4-wire

Signal immediate

Dial-peer voice 7777 pots

Destination-pattern 7777

Port 1/1/0

Ephone-dn 55

Number 5555

Moh out-call 7777

Now we will enable MOH from a live feed and in case live feed is not available, router will sue music file (music-on-hold.au) and multicast address for the audio stream as per the telephony service configuration.

Voice-port 0/1/0

Auto-cut-through

Operation 4-wire

Signal immediate

Timeouts call-disconnect 1

Description MOH Live Feed

Dial-peer voice 7777 pots

Destination-pattern 7777

Port 0/1/0

Telephony-service

Max-ephones 24

Max-dn 192

Ip source-address 10.232.222.30 port 2000

Moh music-on-hold.au

Multicast moh 239.1.1.1 port 2000

Ephone-dn 52

Number 1

Moh out-call 7777

In US moh is considered as broadcasting so license needs to be purchased if you intend to play songs covered by a copyright over MOH. So we can royalty free songs with MOH available on internet.

This concludes lesson of configuring music on hold from an audio file and a live feed on cisco unified CME.