Bluetooth Classic#
Bluetooth Classic (BR/EDR — Basic Rate / Enhanced Data Rate) is the original Bluetooth standard, used here exclusively for audio streaming from the iPhone 16 Pro Max to the Shokz OpenRun Pro 2 headphones.
In the Network#
| Link | Profile | Data |
|---|---|---|
| iPhone 16 Pro Max → Shokz OpenRun Pro 2 | A2DP | Stereo audio (music, podcasts, navigation) |
| iPhone 16 Pro Max ↔ Shokz OpenRun Pro 2 | HFP / HSP | Phone calls, microphone |
Key Specifications#
| Attribute | Spec |
|---|---|
| Frequency band | 2.4 GHz ISM (2402–2480 MHz) |
| Channels | 79 channels × 1 MHz |
| Data rate | Up to 3 Mbps (EDR) |
| Typical range | 10 m (Class 2) |
| Topology | Connection-based (point-to-point) |
Profiles Used#
A2DP (Advanced Audio Distribution Profile) — carries stereo audio from the iPhone to the Shokz. Used for music, podcasts, and turn-by-turn navigation prompts from Apple Maps or third-party apps. A2DP requires Bluetooth Classic because it needs higher bandwidth than BLE can provide for streaming audio.
HFP (Hands-Free Profile) — enables phone calls with microphone audio from the Shokz back to the iPhone. The Shokz dual-microphone array with AI noise reduction filters wind and road noise, making calls intelligible at cycling speeds.
HSP (Headset Profile) — older headset profile, supported by the Shokz for compatibility.
AVRCP (Audio/Video Remote Control Profile) — lets the Shokz button controls manage iPhone playback (play/pause, skip track, volume).
Why Classic Bluetooth for Audio#
Bluetooth Classic predates BLE and was specifically designed for continuous data streaming. A2DP audio requires a sustained ~320–768 kbps throughput for stereo music, which BLE was not designed to handle in its original spec. Bluetooth Classic’s higher-bandwidth radio handles this reliably.
Modern headphones (including the Shokz OpenRun Pro 2) implement both Bluetooth Classic and BLE in the same chip, but audio streaming uses the Classic radio.
Relationship to Bluetooth LE#
Both Bluetooth Classic and Bluetooth LE share the 2.4 GHz band and Bluetooth branding but are distinct radio protocols — a device must explicitly support each one. The iPhone 16 Pro Max supports both. The Apple Watch Ultra 1 supports BLE and uses it for Watch↔iPhone sync, while the iPhone uses Classic for the Shokz audio link simultaneously.