Vivo M, MultiLINE and choice of call number

Hello everyone,

We opted for the pack Vivo M recently with a MultiLINE option with 3 call numbers (1 private line, 1 line reserved for the office and 1 analog line for fax). Both lines are programmed to ring on our 4 DECT HD Phones. In the standard Internet-Box settings, the outgoing stream is the private line for all phones.

With a long press on the call button on HD Phones, there seems to be a choice of the call number, which unfortunately does not work in practice. The call number remains the one programmed in the Internet Box despite the different choice on the HD Phone.

Is there a way to call from the private line by default, but change the call number on an ad hoc basis if it concerns the office?

Thank you in advance and best regards