Managing\Enabling 4 simultaneous calls W56P

[Laz1971]

I need some assistance please.

We recently purchased a W56P Handset and Base combo and our client required both SLA and the ability to manage multiple calls, up to 4 simultaneously from one SIP account on the one device as advertised. Answer a call, put it on hold, answer another call, put it on hold, answer a third call, put it on hold and then answer a fourth call, put that call on hold and then go back and retrieve the second call I had on hold already (example), all the while I have the other three calls still on hold. I am currently doing it with T48G\S phones. I need it (W56P) to behave exactly the same way. I currently assigned all incoming and outgoing calls to be handled by Handset 1.

All of this was managed under Account->Number assignment.

It appears that this is not working. My client insists that he is still only able to answer 2 calls & put on them hold and no more. How do you set up the handset to handle and put on hold 4 simultaneous calls, please?

Thank you in advance!