3CX + W60B + W56H

[Garrett78]

Hello everbody,
We use a 3CX voip phone system in our company in combination with the W60B deck and 5 W56H phones.
All regular except for one thing we can't figure out if it's 3CX switchboard or W60B configuration fault:
once an incoming call is accepted and passed from one user to another, the W56H of the user who passed the call does not ring to the other incoming calls, until the first call is terminated. That is, with an active call on one of the 3 lines we have, 3 phones ring instead of 4.

Thanks for your help

Garrett78 - Italy