Use case for Bluetooth enabled IP phones?

[jolouis]

Just to throw another perspective in here since you said you are relatively new to VoIP.

Your scenario is kind of backwards from what most deployments typically see. In your setup, you are trying to have:
1) External caller -> Cell phone --> Desk Phone (--> PBX --> some other desk phone)

A few downsides to that approach:
1) As you have found, just finding hardware to support it is difficult.
2) Have not done it myself, but I would guess even with at VP-49G or any of the others people have mentioned, I suspect you would not be able to get the second part (Transfer from desk phone to somebody else's phone in the office) to work.
3) If somehow you could get #2 to work, the entire call is still relying on the cell phone to operate, so a) you're using cell minutes b) you're keeping that original cell phone busy until the call is done. c) If the person walks away with their cell while the call is happening, if it went out of Bluetooth range it'd drop.

To avoid all these issues the typical suggestion is to take the idea and turn it upside down, so you end up with a much more typical call flow:
1) External Caller -> Office PBX -> Desk Phone -> Call Forward or Follow-me -> Cell phone

Basically instead of having people call the cell direct, they call a dedicated number on the office PBX that is assigned to the specific desk phone. In the PBX you program things so that the system generates a second call from the PBX out to the cell phone (you can do this using follow-me, or call forwarding). If you're not sure, you can do it directly on the desk phone itself by using the Call Forward feature, and putting in the cell phone # as the "forward to" value.

Advantages to doing this way are:
1) Easily supported. Any Yealink phone will let you do the forwarding on it, or you can do it on PBX as long as your system supports it (virtually all should).
2) Transferring is now possible. Most PBXes have an "in call transfer" feature, so while you're talking on the cell because the call is going through the PBX, you dial that "in call transfer" and the PBX automatically takes the caller and forwards it over to somebody else, hanging up your cell phone. That means you can go off, leave the building, make other calls etc without worry about the other caller.

Of course there's more to it than that, as doing it this way also means you can now do proper central billing/CDR records, etc. Not sure if you're planning to handle the PBX yourself or what, but a VoIP vendor who knows their stuff would be an asset for this kind of thing.