Have you tried googling the installation manual?
Here's a quick excerpt from the manual to give you an idea
Use Program 10-04 : Music on Hold Setup to set the Music on Hold (MOH) source. For internal Music on Hold, the system can provide a service tone callers on hold or one of eleven synthesized selections.
Input Data
Item No.
Item
Input Data
Description
Default
01
Music on Hold Source Selection
0 = Internal MOH (Tone set by PRG 10-04-02)
1 = External MOH (Tone set by PRG 10-60-01: Audio Port No.2)
2 = Service Tone (Tone set by PRG 80-01, tone 64)
3 = VMDB (Tone set by PRG 10-04-02)
• Internal Music Tune - The tune is set by Program 10-04-02.
• External Source - ACI input via audio connector (J421) (Program10-60-01).
• Silence - Callers on hold hear silence.
0
02
Music on Hold Tone Selection
[In case Item 1 is 0.]
1 = Download File1
2 = Download File2
3 = Download File3
[In case Item 1 is 1, 2, or 3.]
1 ~ 100 = VRS Message Number
Download File1 : Farewell Song (by Cho- pin)
Download File2 : Die Forelle (by F. Schu- bert)
Download File3 : Plaisir d’amour (by J.P.E.Martini)
good luck