Problem description:

When Fanvil IP phones register to openscape 4000 IPPBX, they can call each other, and they can call the Siemens IP phones each other too, but hold on music cannot work normally, and the problem details are as follows:

When the internal call happens to two Fanvil IP phones, if we press hold key on one IP phone, another one Fanvil IP phone cannot hear hold on music;
When the internal call happens to Fanvil IP phone and Siemens IP phone, if we press hold key on Fanvil IP phone, the Siemens IP phone cannot hear hold on music; If we press hold key on Siemens IP phone, the Fanvil IP phone can hear hold on music.

Solution:

Firstly, when the internal call happens to two Fanvil IP phones, the capture of the phone which we press hold key is like this:

In the capture, we can find that the Fanvil IP phone sends the re-invite request of hold to the IPPBX.

The capture of another one Fanvil phone is like this:

In the capture, we can find that the IPPBX does not send any re-invite request of hold to the Fanvil phone.

Secondly, because the hold of Siemens IP phone can work normally with the IPPBX, we can make a comparison between Fanvil IP phone and Siemens IP phone when we press hold keys on them.

In the re-invite request of Siemens IP phone, we can find that media attribute is inactive.