Voice Quality Issues with In-Car Bluetooth Systems


I have commented on this several times without much response. Basically I pair the Pebble to my iPhone5 and i also pair my car to my iPhone5. My car has Bluetooth capability and supports placing calls, receiving calls, and two-way audio via Bluetooth on an established call. If the Pebble is NOT connected to my iPhone5 and the car is connected to my iPhone5, the car Bluetooth sound quality is excellent (it always was, absolutely no complaints). However when I connect the Pebble and the car simultaneously to my iPhone5, the car Bluetooth can still place calls and receive calls, however the audio is horrible. Basically it is useless. Now, if i must make a choice, the car Bluetooth is much more important than the Pebble Bluetooth since phone audio is much more important than the benefits of Pebble.

So, I believe there is an issue which hopefully will be reviewed by the Pebble engineering team. I truly am a huge supporter of Pebble but unfortunately the Pebble must sit in a drawer turned off until this issue is resolved.

Is anyone else seeing similar issue? Is it only me? Does anyone else require Bluetooth audio within their car (especially since using a phone in your car is illegal without hands-free support)?

I have heard some responses that this completely has to do with my iPhone5. Well, to that i say hogwash. I will not get rid of my iPhone5 simply because i got a Pebble (rather the Pebble should work with the iPhone5). I also will not give up Bluetooth audio in my car simply because i got a Pebble. I welcome all comments


Until this is fixed why not turn the bluetooth off on the Pebble when in the car? Your phone should only be used as a phone in the car and you get to keep the Pebble out of the drawer.

As a Jailbreaker since day one of availability you may now scream cause I do suggest it but I doubt it would fix this issue… :slight_smile:


Turning off the bluetooth on the Pebble in the car isn’t really acceptable to me. When I turn it back on, I have to go through the Notifications menu and toggle every service I want to work on the Pebble which is a pain if you do it every time you jump into and out of the car. I also notice the deterioration of sound quality with my car’s built in bluetooth phone service. I sure hope they get to the bottom of that one quickly.


I have an iPhone 4 and have it Bluetoothed to a 2011 Ford Edge and I have no problems with the Phone features or quality. I even have a Cobra radar detector that is bluetoothed to my phone at the same time as the Pebble and the sync system without having any problems.

Bob Penn said:
Turning off the bluetooth on the Pebble in the car isn't really acceptable to me. When I turn it back on, I have to go through the Notifications menu and toggle every service I want to work on the Pebble which is a pain if you do it every time you jump into and out of the car. I also notice the deterioration of sound quality with my car's built in bluetooth phone service. I sure hope they get to the bottom of that one quickly.

Try just cycling the Off/On on the pebble. That is what reenables everything for me. Takes about 8 seconds.


I have the exact same issue. If my iphone 5 is connected to pebble, it has a horrible voice quality over my car bluetooth. If I disconnect pebble, everything is fine. I’m certain pebble that pebble is the cause. It doesn’t happen with other bluetooth devices.


I’ve had a bluetooth remote before. Didn’t seem to interfere. I would assume that Apple tests bluetooth interference with more devices than Pebble. So I’m tempted to blame to Pebble on this issue.


I have an iPhone 5, with Pebble and Bluetooth in three cars. Two of the cars have no issues when the Pebble and the car’s Bluetooth are both on and paired with the phone. Those two cars are the same make (Lexus), same model year (2013), different models, but the Bluetooth handsfree implementation appears to be identical. The sound quality is perfect, as it was before the Pebble. The third car is a different make (2013 Honda) than the other two, and when the Pebble and car are both paired, the Bluetooth handsfree sound quality in the car during phone calls is horrible. Fortunately that is not the car I drive regularly.

I am not a Bluetooth software/driver expert, but either the Pebble software needs to take into account different flavors of the Bluetooth handsfree phone protocol, or certain car manufacturers may have older or less supported Bluetooth protocols in their implementations.

Bottom line, it works fine in some cars, not so good in others, and should work perfectly in all cars. Now, is this a Pebble issue, or are some of the car makers to blame?


I don’t think it’s the Pebble itself, I think it seems to be the Bluetooth profile that’s being used. The phone seems to think the watch is an audio device, so at times it has trouble sending data. I’m pretty sure you’re not supposed to have two separate audio devices paired at the same time as it can cause problem even if they’re not both technically “active”, so it seems logical this is the problem. It also causes occasional problems with Siri.

Pebble still uses Bluetooth 2.x unless I missed an update. With the 3.x stack not enabled the phone would have to downgrade the connection to the car in order to use both devices at the same time.
So, TechDoc is correct. Even though 2.x supports those features perhaps your car or doesn't support the higher quality version in the 2.x stack.

I'm not expecting to see Bluetooth stack and profile updates until Q4 or so. Q2-Q3 is most likely still shipping, production, and critical software issues.


My iPhone 4S is Bluetoothed to my Peeble and 2011 Volkswagen Tiguan with no sound issues.


The link posted by whacko has nothing to do with this topic. It’s about general bt issues. Based on Techdoc’s comment and other threads in the forum, I think that pebble has compatibility issues when connecting to certain cars (only iphones). Mine is 2010 Audi. They should test it with a wider range of cars to find and fix the issue. Hopefully it’s a software issue that could be fixed with an update.


This is absolutely not the fault of Pebble, I can say with more than 70% certainty, the first problem is the Car Kit which has decided it must be the Master device of its connection to the iPhone. However the way in which ACL and eSCO packets are scheduled, the iPhone should not be dropping or ignoring eSCO packets just because the Pebble has an ACL connection established too, this is the second problem. Apart from during firmware updates, Pebble should keep the ACL in Sniff mode with intervals of 250ms (400 slots or greater), attempts and timeout values should be 1 or 2 slots. Annoying iPhone will exit Sniff mode if it sees a few RFCOMM packets.


Well, it sounds like it’s not happening with all iphones, and it’s not happening with all car BT equipment. Sadly, the cheaper and more expendable part of the triangle is the pebble, so even if it’s not pebble’s fault, they better look for a “fix” because no one is going to change car or iPhone because of Pebble.

I propose to create a thread with “compatible/incompatible” info, posting:
- Pebble FW version
- Phone model & OS version
- Car model (incl. year) and/or BT equipment model and version.

Sadly, I’m still waiting for my pebbles to arrive, but when they do, I’ll be able to test it with different cars and different phones.


I’m having Bluetooth A2DP issues with my LG Nexus 4 and several headsets when my Pebble is connected, see this thread: http://forums.getpebble.com/discussion/2706/connecting-pebble-and-jawbone-era-simultaneously-android-4-2-2#latest


Ok, i did more testing (by the way, I should state i'm a voice expert). Sorry for the techinal info within the comment below, but it will further state my point.

First, when i tested the iPhone5 on my car, i was not using a 'cheap' car kit, rather it was connected to car's internal Bluetooth (Mercedes CLS 550). I also tried on my wife's car, Acura MDX, with same results. I then connected my phone to my Bluetooth test equipment. Basically this equipment connects any mobile device to Bluetooth and also supports PSTN connections. The test euipment supports call control as well as send/record voice for Voice Quality Testing (VQT). The test equiopment hardware includes a Cambridge Silicon Radio (CSR) Bluetooth Chip, similar to that found in most all Bluetooth headset devices. The Voice Quality algorithm used for this test was ITU-T P.862.1 (PESQ). The scale for the PESQ algorithm is 1-5 (5 being perfect). For all tests, the iPhone is on ATT network whereas the far-end is Verizon PSTN. Each test consisted of 3 different calls, each call sending/recordng 4 voice files. After each test i averaged all PESQ scores.

The average score for iPhone5 without Pebble was 2.71. This is average for mobile to PSTN.

The average score for iPhone5 with Pebble was 1.36. This is considered extremely low.

The average score for iPhone4 without Pebble was 2.40.

The average score for iPhone4 with Pebble was 1.22.

I saved the recorded voice files and, if you listen, you can hear a harsh static (which is why the PESQ scores were so low). This was a lab based test which confirms the Pebble is causing some degredation. I performed a few more iterations of these tests. For instance i unpaired the Pebble to the iPhone5. Repaired, reconnected, and then retested. The scores were much better initially, then got worse. It seems the Pebble is trying to pair to the phone via A2DP and not simply data. I also have an issue that the Pebble shows up on my iPhone as an Audio source (this doesn't make much sense).

Anyway, these are the results and the reason why the Pebble is causing me issues. This should in no way be considered an issue of the Bluetooth headset (or car kit) or an issue of the iPhone5. Pebble should work with the device, rather the device trying to work with Pebble. All comments are welcome.


Pebble presumably shows up as an audio device in order to allow it to control the audio. These seems to confuse some iPhones into thinking that it can play or receive audio via them. fwiw, it doesn’t cause degradation to my bluetooth headphones whether listening to audio or using them for a phone conversation (I’m using Android though.)


I am having the same issue using Pebble, iPhone5, and Acura ZDX internal Bluetooth system - the call quality is choppy and static to the point where I cannot use it with the Pebble. If I turn Pebble off, it works - this is what I will do until some kind of software comes out to hopefully fix the problem.


That was a great analysis Robert. It’s obvious that pebble is in some way causing this issue. I wish the support team could give their take on this. Is this affecting only certain pebbles or is it an issue with all pebbles when used with certain car brands?


From hearing a variety of responses it seems this issue is not Pebble dependent, it is affecting all Pebble watches. However it does seem to be dependent on the phone device. For instance the iPhone (especially iPhone5) is causing issues, however the Android does not seem to cause issues. Unfortunately I do not have other Bluetooth data devices which could be added to my test, so I only tested with Pebble as the data device.

It really is a shame because I like the concept of Pebble and was a big proponent of Pebble, however due to this issue the Pebble is now turned off and in my drawer (seems like a big waste for such an ingenious product).