[General Topics] Menneisyys:
Listen to your Pocket PC on your traditional mono Bluetooth headset and/or use its built-in microphone for PDA-based recording!

(I’ve been constantly receiving questions about all these questions on various Pocket PC boards and newsgroups; now that I’m tired of answering the same question at least five times a day, I’ve decided to dedicate a complete write-up to it.)

I’ve published several articles on A2DP and AVRCP (please see the Bluetooth category in the Smartphone & Pocket PC Magazine Expert Blog), which is a great way to listen to music wirelessly in (almost) Hi-Fi quality and stereo.

The “traditional” headset mode, on the other hand, may be much more useful for much more Pocket PC users because

There are much more cheap, “traditional”, mono Bluetooth headsets than expensive and bulky A2DP stereo headphones. They are available in all phone shops everywhere and are used by, it seems, everywhere. An example of them is the X3 micro, of which Jack Cook has just published an excellent review

To listen to, say, GPS navigation, the (not very good, phone-grade) quality of these headsets may be sufficient

Furthermore, they offer two serious (!) advantages over the A2DP mode, because of which you may want to go for the traditional headset mode instead of the high-quality A2DP mode even if you have a full-blown A2DP stereo headphone:

when you actively connect a headset device to your PDA, you will not only use the PDA-to-headset sound routing, but also the opposite direction. That is, if you, for example, want to use your PDA to record your speech (and that of your environment), and the slightly degraded (recording) sound recording quality (which won’t really be an issue when you only plan to record speech) isn’t an issue, you may want to opt for using your headset to record your speech as opposed to your PDA, which, then, can even be in your pocket or even in your suitcase.

the CPU usage of the “plain” PDA-to- headset unit will be about an order of magnitude less than that of A2DP. For example, on the non-overclocked HTC Wizard, device.exe consumes between 28 and 35% with A2DP, depending on the quality. With simple non-Hi-Fi / non-stereo sound routing, device.exe doesn’t consume anything at all, compared to the default (sound isn’t routed) case. That is, when battery life and / or responsiveness is of paramount importance and the heavy sound quality degradation / lack of stereo, you may want to prefer the low-quality, mono but non-battery-consuming headset mode to high-quality, but heavily battery-consuming mode, which also makes your Pocket PC much less responsive.

Being able to constantly (!) route the sound of your PDA to your mono headset, first, depends on the maker of your built-in Bluetooth stack. In here, Widcomm / Broadcom users (Widcomm is used in most PDA’s with operating systems prior to WM5 except for the Phone Edition models of HTC; as far as WM5 models are concerned, all Acers, HP iPAQs have sticked with this stack; the majority of Fujitsu-Siemens Pocket PC’s (except for the T8x0) and all Dell Axims (which were all Widcomm-based in the pre-WM5 times) have switched to the Microsoft BT stack), as usual, have a lead because they don’t need additional hacks / third-party applications, as opposed to the Microsoft stack.

Widcomm / Broadcom BT stack

The newer Widcomm / Broadcom BT stack versions (starting with BT stack 1.5 built into most Widcomm-based WM2003SE devices; this is also true with 1.6 and the latest 1.7, which is used in current Widcomm-based WM5 Pocket PC’s) all natively support routing the sound to your mono headset (and, of course, vice versa) as can be seen in this and this screenshots. That is, in these devices, just go to Bluetooth Manager / New, switch the headset to discoverable mode and select Hands-free / Headset setup. After creating a shortcut to the connection, just double-click it to connect (or, press the button on your headset / switch it on; then, they may automatically connect. Note that, with some headsets (for example, the Plantronics Pulsar 590A and the Dell Axim x51v with the Widcomm BT hack, the "hacked" (see below) HP iPAQ 2210 or the WM5-upgraded iPAQ hx4700), after connection, you'll need to press the headset button once more, when you hear a ringing sound. It's only then that the sound routing will be started.)

Older Widcomm versions (up to 1.4 built into most pre-WM2003SE Pocket PC’s; for example, the HP iPAQ 2210), however, don’t offer Hands-free / Headset setup in the Bluetooth Manager, in the New / Connect! list as can be seen in the following screenshots: 1 2. There, all you will need to do is

changing HKEY_LOCAL_MACHINE\SOFTWARE\ Widcomm\BtConfig\ Services\0005\ Enabled from 0 to 1 in the Registry as can also be seen in here. After this, a new item, Connect a headset, will be added to the above New / Connect! list as can be seen in here.

changing HKEY_LOCAL_MACHINE\ Drivers\ BuiltIn\ WaveDev\ Dll to btceif.dll. Make sure you export (or, at least, remember) the original name of this if it's different from wavedev.dll - you'll need it when you want to switch back to the built-in speaker.

Note that this tutorial also elaborates on these two steps (it, however, adds no relevant information so you don't have to read it) and I've also uploaded two registry import files to make the switch much easier. Here's the registry import file to enable sound routing and here's the one to disable it. Also note that you must reset your device after applying the registry changes as, unlike the BT stack-only hacks, which "only" make it necessary to restart the BT stack itself, the second, HKEY_LOCAL_MACHINE\ Drivers\ BuiltIn\ WaveDev\ Dll hack, will only be used after a reset because it's a system-wide hack.

After this hack, you can go on as usual: after selecting Connect a headset, the device will find the headset, you just enter the PIN (0000 or, in very few cases, 1234) and, by clicking Finish here, let the system create the shortcut for you.

Note that, despite being able to connect to the headset now, these "hacked" pre-WM2003SE devices are not guaranteed to flawlessly work with the headsets. For example, some HP WM2003 Pocket PC models are known not to be able to use them at all; for example, the HP iPAQ 4150. Unfortunately, in these cases, installing the well-known HP 1.6 BT update (see my A2DP articles on what it is) doesn’t help either: as opposed to the registry hack (which doesn’t help with this BT stack version any more) it won’t list “Connect to headset” (or, as it's called in never, 1.5+ Widcomm versions, Hands-free / Headset setup) any more in New (1 2 3) and, when you directly discover the services of a headset and select the (only) “Headset” profile they offer, connection attempts will always fail.