[Sony Xperia M] Dr Goodvibes:
I have an Sony Xperia M (C1905) with Root access (locked bootloader) running stock Android 4.1.2

The Sony Xperia M (C1905) supports Bluetooth 4.0 (with added features if we get Android 4.3)

I have a Panasonic Link2Cell KX-TG7873S home (landline) phone.

The KX-TG78 Link2Cell home phone has a USB 2.0 cellular charging port which is a nice touch.

The Panasonic KX-TG7873S provides Link2Cell via Bluetooth.

This supports inbound and outbound Cellular calls (Link2Cell), with inbound caller ID read from contacts.

Calls/communications are transferred to and from your cellular phone via Bluetooth.

Another feature is that the DECT KX-TG78 home land phone can pick up the arrival of an inbound txt messages and alert you on your home phone handsets dotted around the house.

The alert is sounded on all home handsets with "Text message!!... Text message!!".

NOW... The Sony Xperia M (C1905) does support Bluetooth Message Access Profile (MAP) and can be paired and will alert you of inbound txt messages.

Problem

HOWEVER... if you stop/disconnect Bluetooth and attempt to reconnect at a later time (arrival home again) it won't successfully re-pair again.

It prompts with a six digit Bluetooth pairing number which can't be accepted by the Panasonic Link2Cell KX-TG7873S land phone.

I do note the Panasonic OUI MAC address is in a Bluetooth blacklist(blocked) in /data/mics/bluetooth, /data/mics/bluetoothd

Not sure this is really stopping anything as I removed it and it's still removed after a reboot.

Before I removed it the OUI MAC address block, the Sony Xperia M was still successfully pairing the first time with the home land phone.

If I remove any reference to the Panasonic KX-TG7873S (Seen as DECT KX-TG78 in Bluetooth list by default) with MAC OUI 00-08-F0, I can successfully pair again.

The Panasonic KX-TG78 Link2Cell does use a default 0000 Bluetooth challenge PIN.

This can be changed on Panasonic KX-TG78 land phone, but again this makes no difference, that I'm aware of.

I have a Sony Xperia S (LT26i) running Android 4.1.2 which is paired to the Panasonic KX-TG78 on the second line and it's working just fine.

I can just turn on Bluetooth at any time and once paired, it just reconnects without problems the next time using Panasonic Link2Cell.

The Sony Xperia S doesn't support Message Access Profile (MAP)

The Sony Xperia S does only have Bluetooth 2.1

So it may be that the Sony Xperia M is having issues when reconnecting due to Bluetooth MAP.

As this is a long shot, I'm wondering if anyone knows how I could manually alter the Bluetooth connection on the Sony Xperia M so that it'll connect to the Panasonic Link2Cell KX-TG78 without having to manually reconfigure Bluetooth each time.

I've use extended naming in the hope a Google search will invite a wider audience where expertise may come from different practices.

[Update MAR-2014]

Panasonic support did reply and thought it may be something better taken up with Sony.

Fair enough, as I'm running Android 4.1.2 and there is upgrades in the pipeline which may include Android 4.3, so we can look at the problem again after an Android upgrade.

[Update APR-2014]

Upgraded to Android 4.3 on my Sony Xperia C1905 and Bluetooth MAP profile how works.