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Bluetooth protocols explained

Understanding the ABCs of Bluetooth in your car

Bluetooth® wireless technology is a natural for the car. Most people know that by "pairing" (connecting wirelessly, in other words) their Bluetooth phones with their car stereo receiver, they'll be able to engage in hands-free calling. But Bluetooth also has other functionality, like wireless streaming of music from smartphones and other Bluetooth devices to your car stereo.

Bluetooth in the car

It does all this by opening up a 2-way line of com­munication between your smartphone and your stereo, letting them have a conversation. You just need to make sure they can speak the same languages.

The easiest way to make sure your phone and stereo do the things you want — like playing music, answering calls, and supporting voice control — is to see if each one is compatible with certain specific Bluetooth protocols. And the easiest way to do that is to check your phone and stereo for the abbreviations we'll discuss below.

Add Bluetooth to your car with a new stereo

Whenever you're shopping for a Bluetooth stereo on our site, you'll find compatible protocols listed on the stereo's "Details" tab, under "Product Research". And remember: for a particular feature to work, both your phone and your stereo need to be compatible with the necessary protocol. So read up, decide what you want, and then get shopping for the car stereo that's right for you.

[Shop for car stereos with Bluetooth connectivity]

Bluetooth logo
Most Common Bluetooth Protocols
Protocol Abbreviation Benefit
Advanced Audio Distribution Protocol A2DP Audio streaming
Audio/Video Remote Control Protocol AVRCP Control over music playback directly from the stereo
Hands-free Profile HFP Hands-free calling through the stereo
Object Push Profile OPP Uploading of contact info to the stereo
Phone Book Access Profile PBAP Access to contact list from the stereo
Bluetooth makes hands-free calling possible

The Bluetooth Hands-free Profile means you can take a call without fumbling with your phone while you drive.

Get hands-free calling

Protocol: Hands-free Profile

Abbreviation: HFP

Most people get Bluetooth in the car for the Hands-Free Profile (HFP), which lets you make and take calls without having to touch your phone. HFP is the same protocol used by Bluetooth headsets for hands-free calling.

The advantage of having a car stereo that works with the hands-free profile is that incoming numbers show up on the stereo’s display, and you hear your callers over your car’s speakers.

When HFP is in action, Bluetooth designates your phone as a "gateway" and your stereo as a "hands-free unit". Your caller's voice passes through the phone and gets sent to your stereo, while your voice passes from an external microphone to your stereo, then to your phone, and on to your caller. Some Bluetooth stereos feature built-in microphones; others come with external microphones that you mount somewhere close to you, like on the sun visor or steering column, then plug into the back of the stereo.

Get access to your phone's contact list

Access your phone contacts through your receiver

Having your stereo access your contacts with the Phone Book Access Protocol makes it easier to place calls in the car.

Protocol: Object Push Profile or Phone Book Access Profile

Abbreviation: OPP, PBAP

Hands-free calling wouldn’t be quite as convenient if you had to use your phone to pull up your contacts. Fortunately, Bluetooth can help in two ways.

The first, and most basic, is with Object Push Profile (OPP). This protocol lets you upload your contacts from your phone to your stereo. How the process works varies by stereo and phone, but basically, you set up a push/pull relationship between your phone and your stereo; you ask your stereo to "pull" the contacts from the phone, while telling your phone to "push" the info to your stereo. Your stereo will also have a limit on the number of contacts you can upload.

The more advanced Phone Book Access Profile (PBAP) lets your stereo tap into your phone’s contacts instead of uploading them. The process typcially intiates itself automatically, and usually goes like this: once your stereo and phone are paired, your stereo will ask your phone, "hey, may I take a peek at your contacts?" Your phone will reply, "I'm not sure, let me check." You'll then get a message from your phone telling you that your stereo is asking to connect with its contact list. All you have to do is approve, and your contacts will show up on your receiver's screen. This makes placing calls much easier.

Many receivers will allow you to engage in voice dialing, but usually only if your phone allows voice dialing. There are a few receivers that will allow voice dialing just by being able to access your phone's contacts.

Enjoy wireless audio streaming

stream music using your bluetooth phone

The Advanced Audio Distribution Profile lets you stream suprisingly good-sounding audio to your compatible stereo.

Protocol: Advanced Audio Distribution Profile

Abbreviation: A2DP

Want to enjoy music from your phone with a pesky tangle of wires? Bluetooth audio streaming makes it happen. As long as your receiver and your phone "speak" Advanced Audio Distribution Profile (A2DP), they’ll make beautiful music together. It’s sure nice to play whatever you have stored on your device without actually having to plug it in. You’ll also be able to hear the audio from most of your smartphone’s music apps. And your backseat passengers can have some fun playing DJ by pairing their devices, too.

So why do they call this profile "Advanced"? It has to do with audio quality: A2DP plays higher-quality mono or stereo audio from formats like MP3 and AAC than standard, narrower Bluetooth audio.

Essentially, A2DP creates a "Source/Sink" relationship between your phone and your stereo, in which your phone, the source, sends signal to your stereo, the sink. A2DP is also used in products such as wireless headphones and wireless speaker systems.

[Shop for car stereos with Bluetooth connectivity]

Get control over music playback

bluetooth enabled receiver

With AVRCP, you get some control over wireless music playback (bottom). With version 1.3 of AVRCP, you get to see artist, album, and song info, too (top).

Protocol: Audio/Video Remote Control Profile

Abbreviation: AVRCP

The Audio/Video Remote Control Profile (AVRCP) allows control from your stereo over the music you’re playing from your phone or device, including songs from apps like Pandora® and Spotify. Bascially, AVRCP turns your stereo into a controller and your phone into a target. Much like a TV remote control, when you push a button on the stereo, AVRCP translates this action into a signal that it then sends to your phone. The end result: the ability to use your stereo's buttons or touchscreen to play, pause, and skip back and forth between tracks.

See song and artist info, too

Protocol: Audio/Video Remote Control Profile

Abbreviation: AVRCP

One of the neat things about connecting your iPod® or iPhone® to your stereo is that it’ll send "metadata" — song, artist, and album title info — to the display. In 2007, version 1.3 of AVRCP was launched, letting Bluetooth do it, too. So now, not only do you get control over your music, you get to see what's playing at all times, even when you're playing music from many popular apps. Newer versions of AVRCP even allow for browsing and manipulation of multiple players.

When it comes to audio playback, AVRCP epitomizes the 2-way communication Bluetooth establishes. Your phone, or other device, sends sound and info to the stereo, while the stereo sends commands to the phone. Sounds like a pretty harmonious relationship to us.

Sound clear?

We hope this article has given you a better understanding of how Bluetooth works. Knowing what to look for in phones and receivers will help you shop with confidence.

If you have any questions or just need a little help choosing the stereo that's right for you, contact one of our advisors.

[Shop for car stereos with Bluetooth connectivity]

Please share your thoughts below.

  • Angel Esparza from Rialto

    Posted on 5/16/2021

    how can I find the pin code to pair my phone though Bluetooth with a axm145bt Axxera ?

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    Ken Nail from Crutchfield

    on 5/17/2021

    Angel - the manual is always the best resource. If you don't have the manual and you bought your gear from Crutchfield, you can call Tech Support for free help setting up your gear. If you purchased your equipment elsewhere, I'd suggest a quick Google search. You shouldn't have any trouble locating the manual.
  • Adrian smith from Cedar Island

    Posted on 1/7/2021

    Hey i just bought a bv765blc radio and i forgot to check about navigation system will i be able to hook up google maps or something in that nature for navigation purposes and it show up on radio screen?

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    Ken Nail from Crutchfield

    on 1/8/2021

    Sorry to let you know, Adrian, that the BV765BLC doesn't support the display of navigation apps from your smartphone. If you have an iPhone, your best bet is to look for a receiver that supports Apple CarPlay. If you're an Android user, Android Auto is the ticket.
  • Helio from Arlington Tx

    Posted on 9/3/2019

    Bluetooth in stereo only works in park mode. Hos can I bypass?

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    Alexander H. from Crutchfield

    on 9/3/2019

    Helio, that shouldn't be the case. If you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.
  • juan san inocencio from Avon, MA

    Posted on 6/11/2019

    Thinking about replacing the radio on my 2014 Honda CRV with navigation system but not sure which radio to choose. Do I need a radio with or without navigation? or can I get a radio without navigation and use the navigation system that is already running in the car?

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    Alexander H. from Crutchfield

    on 6/11/2019

    Juan, you won't be able to retain factory navigation if you step up to a new receiver. So, you'll want to look at navigation receivers or those with Apple CarPlay/Android Auto if you're okay with using the nav apps on your phone. I've passed your question along to our Advisors for help. Someone will contact you soon to help you find the right receiver for your needs and vehicle.
  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 6/28/2017

    Kevin, you'll find the number for our free Tech Support in your emailed receipt. Give us a call and we can troubleshoot the problem with you.

  • Kevin from bismarck

    Posted on 6/27/2017

    Hi, I just bought a Boss BN965BLC from you guys but cant seemto be able to make calls using I need to have the vehicle in park or whats the deal?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 8/10/2016

    Scott, yes, but if you have a particular stereo in mind, be sure to click on the Details tab to confirm compatibility. You'll find your HTC's details in its accompanying manual.

  • Scott from Williston

    Posted on 8/6/2016

    I'm looking to upgrade the stereo in my car to one with Bluetooth capability. Is it a safe assumption that the newest smartphones, like my HTC 10, are compatible with the latest versions of the Bluetooth protocols you discuss in this article?

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    Alexander Hrabe from Crutchfield

    Posted on 7/5/2016

    Gary, I've passed your question along to our sales team. An advisor will contact you soon to help you find the right radio for your F-150.

  • Gary from Aledo

    Posted on 7/2/2016

    Just finished installing 2 pair of Alpine 6x8 speakers in my 1999 F150 I got from you guys and am now looking for a Pioneer or Alpine single Vin CD receiver with bluetooth compatability with an I-phone 4. I read the article but it was greek to me. Any suggestions would be appreciated. My perfect unit would have a front AUX and USB port as well as HD radio. Thanks!

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 6/27/2016

    Nick, given the option between aptX and standard Bluetooth streaming, I'd opt for aptX hands-down. You'll gain a more robust, detailed sound. In fact, we recently conducted a listening test with Crutchfield advisors and they were all impressed with the noticeable difference. You can find out more details about aptX in this article. All of that said, keep in mind that whatever device you're using as a music source must be aptX-equipped. You'll find a complete list of compatible devices here.

  • Nick from Cincinnati

    Posted on 6/25/2016

    Is there a noticeable difference between units that have aptX Bluetooth and those that do not?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 5/19/2016

    Adam, yikes, that sounds frustrating. By now I'm sure you've tried adjusting the Bluetooth volume in your phone settings and in the stereo's Bluetooth settings, but if you haven't, that's the first thing to do. Also, keep in mind that if you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.

  • Adam Ferguson from Kannapolis

    Posted on 5/17/2016

    I purchased a JVC KW-V51BT and paid to have it professionally installed in my 2004 Silverado 2500hd. The radio and cd player functions perfectly with great sound. However, I'm having an issue with Bluetooth. My phone (Samsung Galaxy S5 - Verizon) pairs with the JVC just fin , but I get no audio output in Bluetooth. For instance when using Pandora, I can see the song playing on the screen and it shows the artist/title/time/etc. But absolutely no audio. Same thing when making phone calls. Shows the caller/phone number/etc but still no audio. Even when I connect by Mhl/HDMI cable, I have visuals but no sound (not surprising since you have to have Bluetooth for sound even with cables connected) . I wondered if my phone wasn't compatible but I see videos all over YouTube with people using the Samsung Galaxy S5 with the JVC KW-V51BT. JVC tech support has been absolutely no help. I even returned my JVC in exchange for another and have the same exact issue.what else can i do?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 3/31/2016

    Mike, you'll have hands-free calling and audio streaming capability via Bluetooth with your iPhone 6. Since the DDX5901HD predated the iPhone 6, other features may not be guaranteed. However, two firmware updates are available for this model and may correct this. Check out Kenwood's site for details.

  • Mike from Murrells Inlet

    Posted on 3/29/2016

    Does the Kenwood excelon ddx5901hd support the iPhone 6s?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 3/15/2016

    Justin, you'll need to confirm the Bluetooth protocols of your phone, but if it's a recent model, you will likely have this level of functionality. To answer your question directly: yes, think of your car audio system as a very large version of your headset. A Bluetooth-equipped receiver will interface with voice command features on your phone. An external mic wired to the receiver will hear your commands, and you'll hear resulting audio from the phone through your car speakers. The same is true for hands-free calling.

  • Justin

    Posted on 3/14/2016

    With my Motorola Bluetooth headset I can hit the phone button and activate Google Now to use any voice commands through the microphone. Will a higher end Kenwood single din (KDC-BT958HD) or Alpine do this when I hit the phone button? I need this voice pass through functionality to sent texts, make calls, and start navigation with voice commands.

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 3/8/2016

    Ken, your Pioneer MVH-X370BT is a Bluetooth 3.0 stereo and your phone is a Bluetooth 4.0 device. There may be some newer features of Bluetooth 4.0 that you can't use with your Pioneer stereo, but you will be able to make phone calls and stream music.

  • Ken from Columbia

    Posted on 3/4/2016

    Is the Pioneer MVH-X370BT compatible with the Samsung Galaxy S4 for streaming music and receiving phone calls?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 2/29/2016

    Derek, that stereo doesn't appear to have direct compatibility with your phone. So, you'll need to install a Bluetooth adapter, an AUX input, or new stereo equipped with both in your vehicle. We can help you with any of those choices. Just give us a call.

  • Derek quinones from Fremont

    Posted on 2/28/2016

    What do I need so I can play pandora from my iPhone 5 on my alpine cda-117?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 1/24/2016

    Drew, if you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, it would be worth checking Kenwood's site and/or their tech support to see if there is a firmware update that would allow the pairing. We no longer carry this receiver, but at the time, the receiver was only compatible with iPhone models up to 4. Toggling Bluetooth on your iPhone off and then on might also help when you pair next time. Worth a shot.

  • Drew from New York

    Posted on 1/22/2016

    My iPhone 5 is paired with a Kenwood KDC-BT645U.. However it does not wirelessly stream music. In this case, does that mean this head unit does not have A2DP?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 12/28/2015

    Bluetooth issues are not uncommon with the iPhone 6. If you own an Android device or have one available to you, it would be worth pairing it with your Jensen to see if the same problem arises. If it does, then it could be the Jensen that is faulty. If it doesn't, it may be your iPhone. Check for the latest iOS update. Follow the instructions for pairing provided in the Jensen manual. If that doesn't improve things, you may have the best luck by making sure that your iPhone is "awake" to pair before you start your car. Toggling Bluetooth on your iPhone off and then on might also help. Also, is it possible that another device, besides your iPhone, has been paired with the Jensen at some point and is a default device? It may be bumping the iPhone off. Hopefully this helps you pinpoint the source of the problem. Good luck!

  • Perry from Glennville

    Posted on 12/27/2015

    I can't get my iPhone 6 to pair with the Jensen heavy duty radio that has the A2DP the phone will find the radio but the radio just says pairing the whole time.

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    Ken Nail from Crutchfield

    Posted on 12/1/2015

    Mike -- thanks for your question about aptX -- it's a good one. Strictly speaking, aptX isn't a Bluetooth protocol, in that it doesn't have any control or display functions. But if you care about sound quality, you may be interested. Simply put, aptX allows near CD-quality audio streaming between aptX enabled devices, a step up from the audio-streaming quality of most Bluetooth devices. If you'd like to know more about aptX, Qualcomm Technologies (the owner of the technology) has a very good website that explains the basics. You can find it at:

  • Mike

    Posted on 11/30/2015

    So what does aptX mean?? Nowhere in this whole article??

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 9/10/2015

    Julio, yes, it is!

  • julio from laredo

    Posted on 9/9/2015

    Is this stereoPioneer MVH-X380BT (2015 Model) compatible with an iphone 6(Bluetooth) for streaming music

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 9/4/2015

    Alan, according to the manual, the factory default pairing code is "5309".

  • Alan Williams from Portland, OR

    Posted on 9/3/2015

    how do I obtain a pairing code to facilitate linking or syncing my Jensen vx7022 with my i phone?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 8/11/2015

    Jorge, here's a list of stereos that are "SiriusXM-ready" which means you'll need an add-on SiriusXM tuner as well as a subscription.

  • jorge from ny

    Posted on 8/11/2015

    Can this player sopport satelite radio ( uplander wheel control)

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 8/3/2015

    Rowena, if your new Pioneer stereo is Bluetooth compatible, more than likely it can be paired with several phones (although not at once -- typically one takes primary position). So, you should be able to access your phone contacts when your phone is paired. In regards to satellite radio, if your stereo is "SiriusXM-Ready," you can install this tuner in order to receive that service.


    Posted on 8/2/2015

    I just had this Pioneer HD Radio, installed in my 2015 chevy Malibu LS, because I wanted SiriusXM this model did not come with it. My husband set his iPhone up on it and now I do not know if the it will except all my numbers.

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    Ken Nail from Crutchfield

    Posted on 7/20/2015

    Hey David, sorry about the snag you're running into with your phone's addresses. Although you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.

  • David Cross from Berry Creek CA

    Posted on 7/19/2015

    I am having problems with blue tooth putting addresses into the radio. I have a Samsung GalaxyS4 smartphone. How do I program contacts into my radio? I have the JVC KW-V 21 BT Radio. Please try to write the info for what I need to do? Or should I take it back to Best Buy to have them trouble shoot the problem?

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 7/6/2015

    Joe, if you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details. Alternatively, you could give Clarion tech support a call at 1-800-GO-CLARION.

  • Joe from oregon

    Posted on 7/3/2015

    Just purchased a Clarion Marine Stereo CMS2 and it will not pair Bluetooth with my iPhone 4 or 5s. Just doesn't recognize either one.

  • Michael

    Posted on 6/26/2015

    very clear informative article.

  • Commenter image

    Robert Ferency-Viars from Crutchfield

    Posted on 6/17/2015

    Terry, I don't have a sure-fire solution for you, but I do see in our information that the stereo might be limited to a 32 GB thumb drive. You've probably already tried a smaller drive, but if not, it's something. Similarly, there are often limits to the number files and folders you can have on the drive. So try smaller drives with smaller libraries. If you purchased the Pioneer from us, give us a call and our tech support team might be able to help you troubleshoot further. Good luck.

  • terry wildeman from United States

    Posted on 6/16/2015

    I bought a pioneer avh-x7700 and really like it but I can't make a USB drive display in the USB socket. Pioneer told me study what its compatible with and I tried settings in my computer and have bought several USB drives and only audio shows up. What do I have to do just to make a 64 gig stick with 20 movies and 100 cds or so play so I can tuck the USB up under the dash and have the cord availabile for future upgrades. By the way it did work to get the 3.1 upgrade that also helped the codec problem. Thank You T

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 6/5/2015

    Jim, the features that the all-in-one nuviCam gives you via Bluetooth are the same that a car stereo would give you. You would have to choose whether you are going to pair your smartphone with the car stereo or the nuviCam, since they're both offering the same basic feature — giving you hands-free calling functionality (or music streaming, although you'd probably prefer to direct your music through your car speakers rather than through the nuviCam speaker). You can't split the Bluetooth signal output of your phone to two different devices at once (at least, not yet). However, if you're still interested in a new car stereo, a great start is to use our vehicle selector to confirm which stereos fit your car.

  • Jim Jernigan from 23235

    Posted on 6/4/2015

    Can you connect more than one bluetooth device at a time? I just purchased a NuviCam and would like to use the advanced GPS features but would prefer to use a blutooth stereo for my calls and maybe streaming music? Is this possible?

  • Commenter image

    Ken Nail from Crutchfield

    Posted on 5/6/2015

    Alan, great question about your Pioneer receiver. No doubt about it, adding Bluetooth to a home stereo adds a whole new level of functionality to it. To look at your options, we sent your question to our sales team - they'll be contacting you via email soon. For immediate help, you can contact them via phone or chat.

  • Commenter image

    Alexander Hrabe from Crutchfield

    Posted on 5/4/2015

    Larry, The Kenwood Excelon DDX-5902 does not explicitly cite the Razr Maxx as compatible with its mirroring mode. Even with a compatible phone, however, it's important to note that an HDMI cord will be required to engage mirroring mode. Mirroring mode in this specific receiver does not allow touch control of Android apps on the receiver, but it does allow you to view them in-dash, which would still be useful in the case of Google Maps. Buying a receiver based solely on current Android phone compatibility can be tricky, depending on how soon you plan on upgrading to a new phone. Give us a call at the number above, and an advisor can help you choose a receiver based on your phone status and what sort of functionality you need most out of a receiver.

  • Larry Hendricks from 58458

    Posted on 5/2/2015

    I have a Razr Maxx and I am considering the purchase of a Exelon DDX-5902. My question: Can Google Maps be sent from the phone to the 5902?? Can any Android navigation app be exported to the 5902?? If the 5902 can't do this , which Exelon can? Thank you,

  • Alan Rodney from United States

    Posted on 5/2/2015

    Are any specific bluetooth dongle devices available that are compatible with Pioneer VSX 1021 receiver since discontinuation of the Pioneer AS-BT100 - Bluetooth audio adapter?

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