Asterisk Call Center: Music On Hold (Latest Versions)

When callers are waiting in a queue, silence feels like a broken system. Music on Hold (MOH) keeps callers engaged and reduces hang-ups, while also making your call center feel professional.

In modern Asterisk deployments, Music on Hold is used in:

• Call queues
• Call transfers
• IVR hold states
• Agent consult calls

This guide explains how Music on Hold works in latest Asterisk (PJSIP), how to configure it cleanly, and how to troubleshoot audio issues.

What Is Music on Hold in Asterisk?

Music on Hold is audio played to a caller while they are placed on hold or waiting in a queue.

Asterisk supports different Music on Hold classes, allowing different departments to play different audio.

Where Music on Hold Is Configured

Music on Hold configuration file:

/etc/asterisk/musiconhold.conf

Common audio storage path:

/var/lib/asterisk/moh/

Step 1 — Create a Music on Hold Folder

Example: create a folder for a support queue:

sudo mkdir -p /var/lib/asterisk/moh/support

Copy audio files into the folder (wav recommended).

Then set permissions:

sudo chown -R asterisk:asterisk /var/lib/asterisk/moh/support

Step 2 — Configure a MOH Class

Edit:

sudo nano /etc/asterisk/musiconhold.conf

Example MOH class:

[support]
mode=files
directory=/var/lib/asterisk/moh/support
random=yes

Meaning:

• mode=files → play audio files from directory
• random=yes → random playback order

Step 3 — Reload Music on Hold

asterisk -rx "moh reload"

Verify classes:

asterisk -rx "mोह show classes"

If your terminal does not show it, use:

asterisk -rx "moh show classes"

Step 4 — Attach MOH to a Queue

In /etc/asterisk/queues.conf:

[support]
musicclass=support
strategy=leastrecent
timeout=20
retry=5
maxlen=0

Reload queues:

asterisk -rx "queue reload all"

Testing Music on Hold (Quick Dialplan Test)

You can test MOH without a queue:

[from-internal]
exten => 600,1,Answer()
 same => n,MusicOnHold(support)
 same => n,Hangup()

Call extension 600 from any phone and confirm audio plays.

Audio File Requirements for Best Results

For telephony compatibility, use audio files in:

• Mono
• 8000 Hz sample rate
• 16-bit PCM wav preferred

Converting audio incorrectly is a common reason MOH sounds distorted.

Common Music on Hold Problems and Fixes

Caller Hears Silence

• MOH directory path wrong
• No audio files in folder
• Wrong permissions for asterisk user

Music Plays But Sounds Choppy

• Codec mismatch (Opus vs G.711 vs PCM)
• CPU overload on server
• Network jitter causing RTP issues

Music Works Internally but Not for Trunks

• RTP/NAT problem — caller cannot receive media
• Firewall blocking RTP ports

Best Practices for Production Call Centers

• Use different MOH classes for different departments
• Use short loopable tracks, not full songs
• Keep volume normalized (avoid sudden spikes)
• Test MOH from external trunk, not only internal calls

Music on Hold is part of customer experience, not just a technical feature.

Key Takeaway

Music on Hold prevents callers from hanging up and makes your call center sound professional.

Configure MOH classes in musiconhold.conf, attach them to queues using musicclass, and always test audio end-to-end through trunks to confirm RTP and codecs are working correctly.