Bluetooth headsets as virtual headsets in a PBX
It's nice to have a headset on your desk telephone, for handsfree conversations. A number of phones have a headset jack, either of the submini plug used by cell phones, or using a phone handset jack. Many companies buy headset units that plug into the handset line to provide a headset, some of them are even wireless.
But bluetooth headsets today are cheap, standardized and have a competitive market. And they are of course wireless. Many people already have them for their cell phone. I have seen a very small number of desk phones support having a bluetooth headset, and that shouldn't be al that expensive, but it's rare and only on high-end phones.
Here's the idea: Put bluetooth headset support into the PBX. Bluetooth headsets can't dial, they can effectively only go on-hook and off-hook with a single button. You would associate (in the PBX) your bluetooth headset with your desk phone. A bluetooth master would be not too far from your desk, and tied into the PBX, or into a PC that talks to the PBX. When your BT headset was in range of this master, it would be tied to ith with Bluetooth. (You would have to do an actual bluetooth pairing in advance. In addition, many people have bluetooth headsets normally linked to their cell phone, and call attempts from the headset go to the cell phone. The system would have to switch that over to the PBX.) Anyway, once tied, any phone call to your desk phone would also call to your headset. You could answer it on your desk phone or on your headset, as you choose. Caller-ID would appear on the desk phone of course. (Some few bluetooth devices can also show this.)
In addition, if you answered or made a call on the desk phone, the magic association would trigger a special behaviour. If you placed an outgoing connection from the bluetooth headset (by pushing the button on it) and the desk phone had a call, that call would be grabbed from the desk phone and now connect to the headset. This should happen even if (especially if) the call on the main phone is on hold, though if more than one call is on hold it would have to pick one, probably the most recent one.)
This would be very much like having a bluetooth headset tied to the phone, except the phone knows nothing of this and has no special support for bluetooth. In fact, the phone could be a plain old analog phone that many PBXs allow connection to. It would work on any phone out there.
There could also be a magic extension that you could transfer calls to from any desk phone capable of transfer. This would cause the BT headset to "ring" and pushing its button would take the call. However, the one button pickup is even better. Transfer would allow transfer from any phone in theory.
(Optionally, the transfers to the bluetooth headset could be bridges, where the main phone and BT phone are both in on the call, as in a 3-way call, with the main phone hung up if it's not needed.)
If the bluetooth call is hung up, this could cause an immediate transfer of the call to the desk phone. The desk phone would ring, and the caller would be there. This would allow you to do things with the call you can't do from a buttonless bluetooth headset, such as transfer it to somebody else. If you really meant to hang up, you would just pick up and hang up the desk phone. This isn't perfect, and the behaviour could depend on how the BT headset was given the call, whether you are near your desk phone (we know that from signal strength) or user selected options. One trick might be to have the BT headset immediately re-attempt a call after hanging up, and then quickly hang that up.
If you activated the BT headset with no call taking place on the main phone, you could connect the user to some sort of speech recognition system, if you had one, and let them issue commands. That's nice but beyond the scope of this idea.
The key plan here is that the link to the bluetooth headset is done in the PBX (with possible ties to PCs around the office.) That means the phones need do nothing, and they suddenly all support bluetooth headsets.
There are some limits. A single bluetooth master can support only 8 headsets, typically, and having them all going at once can create a noisy environment. However, you can have multiple masters -- USB bluetooth dongles are cheap.
In many cases, you would want a small program on a bluetooth equipped computer to be the gateway to the headset for a user, since many will not be within 100' of the PBX. For IPPBXs this can be something very similar to an IP softphone with a few minor tweaks. Indeed, the use of a "headset only softphone" could be handy even without bluetooth, since it's usually very cheap and easy to get a headset for a PC. In this case, the key feature is the idea that the softphone is tied to the main phone, and a simple command on the softphone grabs any call on the main phone, just like pushing the "headset" button on a desk phone equipped for such operations does.
I'm encouraging this as a feature for Asterisk, the open source PBX I use. It would fit nicely there. Wish I had the time to code it. There are some bluetooth modules under development there in the opposite direction -- to allow the PBX to pretend to be a headset and use cell phones as trunk connections. This also allows some very cool stuff.