[Closed] A techy Bluetooth question

I know I can attach several devices (bose speaker, headphones, etc) to my phone, but my speakers will only connect with one device at a time. Same for the car radio.

It seems to be possible but not sure how you enforce it. An iPhone can be paired to many Apple Watches but Apple Watch can only be paired to one phone. I’ve not successfully sussed out how to pair my Apple Watch to both my personal and business iPhones so assume it’s not possible.

That's not quite the question I'm asking. Some devices can connect to multiple devices simultaneously, some can only connect to one at a time, I get that.

What I want to know is whether a device can enforce that a second device (which is otherwise able to connect to multiple devices simultaneously) cannot be connected to any other devices when it is connected to the first device.

Seems unlikely.

I think Bluetooth has the concept of host and peripheral. So the computer is the host and is in charge, the other things are subordinate. Phones can play both roles.

So headphones are peripherals and I'd expect that as such they cannot tell the host what to do.

Dunno if this is the same thing but I have 2 Sony bluetooth speakers.They have to be linked together first before connecting to my amp to get stereo.I can connect to one speaker on it's own no problem but then can't connect to the second as well unless they have been linked first so in effect becoming one device.

So headphones are peripherals and I’d expect that as such they cannot tell the host what to do.

Ah,but what I'm asking is that if the laptop is the host, can it tell the peripheral (the headphones) that they can't connect to another host whilst connected to it.

I would expect most headphones to do that?

My AirPods certainly do, they connect to the first device but won’t jump to a second device as long as the first connection is still active.

If that behaviour isn’t programmed into your headphones, I doubt you can change it at a consumer level.

Never seen that on consumer Bluetooth devices, my BT headphones can be paired to multiple sources simultaneously but only have one active connection.  However the ‘base station’ on BT based office headsets (Plantronics Voyager for example) has an enforced connection to just one device, if another one is paired to the base the old one is removed.

DECT is probably the technology to use if you want exclusivity of connection.

Ah,but what I’m asking is that if the laptop is the host, can it tell the peripheral (the headphones) that they can’t connect to another host whilst connected to it.

As above I've never known a device to poach a connection. What exactly is happening for you?

I get a similar problem
My bluetooth headphones get superseeded by the car bluetooth when I turn the key on the car.

Ah,but what I’m asking is that if the laptop is the host, can it tell the peripheral (the headphones) that they can’t connect to another host whilst connected to it.

I don't think so. I've only done a little messing with Bluetooth (I've set a raspberry pi to scan local Bluetooth devices to see who's at home) and I think that BT devices only advertise their presence when they're not connected I something.
So once they're connected they are invisible to other hosts and therefore cannot connect to them anyway.
Might be wrong though.

I get a similar problem
My bluetooth headphones get superseeded by the car bluetooth when I turn the key on the car.

Phones may have a hierarchy of connections with cars at the top.

You're essentially asking if a master can prevent a slave from participating in a scatternet and I don't think that's possible. It might be possible if the slave had implemented a custom BT profile that allowed a master connection to do this but even if that's achievable (I know very little about the BT standard and protocol stack) I doubt anyone has done it. Most BT devices don't support scatternets though so is your question based on general security-related curiosity or do you actually have a device that is doing it and you need to prevent it happening?

Cheers for the answers so far.

My question is based on mild curiosity. I have some Jabra earbuds that can connect to multiple devices at a time and for ages they happily connected to my work Win10 laptop and my phone simultaneously. However, there was an issue with the laptops where they weren't recognising the microphones in Bluetooth headsets, and a patch was rolled out to fix it in the past week or so.

Post-patch, my earbuds will connect to only one of either my laptop OR my phone at one time, never both simultaneously. I've done the whole forget device, re-pair device thing on both the laptop and the phone, but to no avail. So, I wondered if there was something in the patch that had implemented an enforced 'unique' connection with any connected device.

My suspicions were raised as where I work is a) pretty paranoid about data leakage and b) has a habit of customising the most simple standard so it doesn't quite work as well as it could...

Is there a reason why you would want your earbuds to connect to two hosts simultaneously? Kinda sounds like they're working as they should now.

Is there a reason why you would want your earbuds to connect to two hosts simultaneously?

I can get calls via a variety of VOIP services on my laptop, or on the phone. It's really useful to be able just to take the call on the headphones whatever route it arrived by.

Is there a reason why you would want your earbuds to connect to two hosts simultaneously?

Yep, this one:

I can get calls via a variety of VOIP services on my laptop, or on the phone and I listen to music most times I'm not on calls. It’s really useful to be able to be listening to my music and just to take the call on the headphones whatever route it arrived by.

If your organisation is paranoid about data leakage, they would have likely disabled Bluetooth on your laptop.

A slightly more likely scenario is that BT headphones used to be limited to a number of source/device profiles - for example 1 telephony, 1 streaming audio.  If your laptop is now broadcasting as multiple profiles (to enable streaming audio and telephony) then it may have used up all the profile connections on the headphones.

can you connect the headphones to multiple phones/tablets simultaneously?  Mobile devices usually announce themselves as 1 profile.  Bluetooth on Windows laptops has always been a lucky dip on what you get (if anything at all).