I asked my Bluetooth representative why my devices don't always connect properly and learned the hard truth.

I asked Bluetooth representatives why our devices are not always properly connected – and have experienced the hard truth

Why is the wireless connection with two devices for your headphones and earphones so unreliable? It is the gaping gap between actual product specifications and marketing language. The Bluetooth connectivity for two devices, also called “multipoint”, is not an official function or specification. It is an application of Bluetooth technologies that is used differently by each manufacturer. Another migration from Bluetooth Classic to LE Audio promises improvements. Bluetooth Multipoint is an important sales argument with which manufacturers of headphones and earphones attract consumers. With this function, a headphone can maintain individual connections with two (sometimes three) devices and switch the sound between them without manually decoupling and recoupling the devices. However, this feature can be unreliable as it separates the connection to the device you want to stay connected to, or feeds audio from the device you do not want to hear. There is a reason for this inconsistent behavior: Multipoint, as it is presented to consumers, is not an official function or specification of Bluetooth. The term is mostly from the marketing language. I spoke to Henry Wong, Head of Market Development at Bluetooth SIG, to understand how Multipoint works and how not, and whether another Bluetooth Classic to LE Audio can fix its deficiencies. How does Bluetooth Multipoint work? If a manufacturer allows this, many headphones and earphones can simultaneously maintain a connection with two source devices, for example a smartphone and a laptop. These are individual one-to-one Bluetooth connections, but you can switch between them without separating and connecting your devices. This feature is often referred to as Bluetooth Multipoint, but since it is not an authorized Bluetooth function, there is no official name for it, which is why Apple they call Seamless Device Switching. “[Bluetooth Multipoint] is not a specification,” says Wong. “Multipoint is an application of Bluetooth functions that manufacturers build on the Bluetooth toolbox.”

To better understand the Bluetooth multipoint connectivity, you need to understand Bluetooth profiles. As Wong explains, you can imagine Bluetooth as a huge toolbox and profiles as the tools in it. Manufacturers can choose which Bluetooth profiles, codecs and functions they want to implement in their devices, and each profile serves a different wireless function. A wireless mouse and wireless earphones do not need the same profiles. Bluetooth-enabled headphones generally support a number of profiles:

Handset Profile (HSP): Allows basic wireless functions between headphones and a source device. Advanced Audio Distribution Profile (A2DP): Allows wireless stereo audio streaming. Audio/video remote control profile (AVRCP): Enables headphones that function as wireless remote control to control audio playback/pause and volume on your coupled device. Suppose you have a headphone connected both to your laptop and to your phone. While you watch YouTube on your laptop with the headphones, A2DP and AVRCP are active. Then you get an incoming call on your phone and your headphones should prioritize HFP when replying. However, a frustrating example is watching YouTube on your laptop with headphones, only that your connected smartphone interrupts your video every time you get a notification. Notifications can trigger HFP and disrupt your stream for a short time. This interruption is not an error; It's just how Bluetooth technology works. Why is Multipoint sometimes unreliable? Since Bluetooth Multipoint is not an official Bluetooth function, but an application of Bluetooth profiles, the interaction of these profiles lies with manufacturers. For example, if you have connected a Sony headphone to a Lenovo laptop and an iPhone at the same time, it is unclear how the headphones recognize what connection should be prioritized. In case of an incoming call, the HFP sends the ringtone of your phone to your ear. It can be difficult to get in touch with your phone while you receive the call, or to disconnect and restore the connection to your other media player automatically. This is due to differences between manufacturers. “If you buy headphones from the brand A, a brand B laptop and a C tablet, it’s different manufacturers, different Bluetooth chipsets and different Bluetooth stack applications,” says Wong. “In most cases, it is not consistent to be able to switch between them.”

A discrepancy between your intention and the behavior of your headphones can be attributed to a simple mixing of connectivity between three different manufacturers, none of which optimizes Bluetooth for the devices of the other. “How your headset manages the logic and priorities of these different applications really depends on the manufacturer,” says Wong. “That’s why there can be inconsistencies between these devices.”

Why device change works in a closed ecosystem

Apple and Samsung have closed device ecosystems and both deviate from the term “multipoint” and instead opt for differentiated brand terms – Seamless Device Switching or Dual audio. In these closed ecosystems, a manufacturer has complete control over how its devices communicate via Bluetooth. “These companies make these [connect] transitions very good, and they do not even call it “multipoint” because it is not really a function, but as they have built it on Bluetooth,” says Wong. This uniform level of control allows companies such as Apple and Samsung to have minimal friction, expulsion and unreliability when switching Bluetooth connections. Like any other manufacturer, these connections use basic, standardized Bluetooth technologies for detection and connection initiation, but according to Wong, proprietary optimizations of the user experience are the key. “These are individual connections, but as they determine which will be changed next is the money earner of this function,” he says. “They have the magic behind the scenes to make everything smooth.”

How to help LE Audio

The Bluetooth profiles used for multipoint connections are based on the Bluetooth Classic radio, the original version of Bluetooth connectivity introduced at the end of the 1990s. As an older technology, it delivers poorer audio quality in connection with headphones, less stable connections and consumes more power than the Bluetooth Low Energy (BLE) protocol. Since Bluetooth Multipoint is not an official Bluetooth function, there is no replacement or a direct improvement, embedded in BLE or LE Audio. However, by introducing modern profiles such as Telephony and Media Audio Profile (TMAP) and Basic Audio Profile (BAP), A2DP, HFP and HSP manage to improve connection transitions between telephone calls and media playback, provide higher playback and reduce power consumption. Apart from the commitment to closed ecosystems, there are no decisions that consumers can make to ensure a smoother multipoint experience. Bluetooth SIG has always emphasized this point in our conversations: it is at the sole discretion of manufacturers which Bluetooth functions are available in a pair of headphones or earphones, and in their marketing materials it is usually not specified which profiles, which versions of these profiles or how they work. The greatest hope of consumers is that manufacturers continue to use LE Audio and not just BLE. BLE alone can’t stream audio while LE Audio offers modern audio features such as the LC3 codec, auracast and TMAP that better meet current complex audio streaming requirements.