I am new to OXO VOIP and need a bit of help. We have a hotel with OXO and they complain that when the guest in the room calls the reception to have them transfer him/her to the SPA, they try to transfer, the phone rings but when they pick up there is no sound. They have to ask the SPA employees to call the guest directly.
What is misconfigured? I tried to check the documentation but could not find anything. Might have looked the wrong way

Thanks in advance for any help.
Kind Regards
Orsy