AT&T MERLIN LEGEND System Reference Manual page 289

Features
Music-on-Hold
Description
Considerations
Feature Interactions
Callback
Camp-on
2-240 Music-on-Hold
Music-on-Hold provides music or recorded information to an outside caller
during the following instances:
When on hold
While waiting in a calling group queue for an available calling group member
After using Remote Access, while waiting for a busy trunk pool (Hybrid/PBX
only)
While waiting in the Callback queue for a busy extension
While camped-on to a busy extension
While on hold for a conference
While parked
While being transferred
The music source or recorded announcement device must be connected to a
ground-start or loop-start line jack programmed for Music-on-Hold. Only one
Music-on-Hold port is allowed per system.
Note: If you use equipment that rebroadcasts music or other copyrighted
materials, you may be required to obtain a copyright license from or pay fees to
a third party such as the American Society of Composers, Artists, and
Producers (ASCAP) or Broadcast Music Incorporated (BMI). Or you can
purchase a Magic on Hold® system, which does not require you to obtain such
a license, from AT&T or your authoried dealer.
Music-on-Hold is not provided to inside callers.
A maximum of one Music-On-Hold port is allowed per system.
DID and tie-trunk jacks cannot be used for Music-on-Hold.
A line/trunk jack designated for Music-on-Hold cannot be grouped in a pool.
An outside caller waiting in the Callback queue hears Music-on-Hold.
When Camp-On is used to complete a transfer of an outside call to a busy
extension, the caller hears ringback and not Music-on-Hold if Music-on-Hold is
programmed as the transfer audible. If Camp-On is used to complete a transfer
of an outside call to an extension that is not busy, the caller hears ringback
instead of Music-on-Hold.