BC127 Doesn't Work with iOS - Missing CTKD Support

IoT Modules WiFi and Bluetooth Modules
1

Hi Sierra Wireless,

I’m an iOS developer using your BC127 module. I’ve hit a major problem, it doesn’t properly support iOS Bluetooth.

The Issue: When I connect to BC127 via BLE on iPhone, the audio (Classic Bluetooth) doesn’t connect automatically. Users have to manually go to Settings → Bluetooth and tap the device every time. This is terrible UX.

Why It’s Happening: iOS requires CTKD (Cross-Transport Key Derivation) to automatically connect both BLE and Classic together. BC127 doesn’t support this.

Here’s what should happen on iOS:

  1. App connects via BLE

  2. iOS automatically connects Classic Bluetooth too (using CTKD)

  3. Everything just works

Here’s what actually happens:

  1. App connects via BLE :white_check_mark:

  2. Classic Bluetooth stays disconnected :cross_mark:

  3. User confused why no audio

I’ve Tested:

  • Multiple iPhones (iOS 13-18)

  • Used CoreBluetooth with transport bridging enabled

  • Tried apps like nRF Connect and LightBlue

  • Same problem everywhere

Android Works Fine: Android can handle missing CTKD. iOS can’t - it’s mandatory since iOS 13.

My Questions:

  1. Why doesn’t BC127 support CTKD when the hardware can do it?

  2. Is there any firmware version that fixes this?

  3. Can you provide a solution for iOS compatibility?

What This Means: We can’t ship our iOS app with BC127. Every user complains audio doesn’t work. They think our app is broken when it’s actually the Bluetooth module.

Please advise on how to resolve this iOS incompatibility.

Thanks,

2

I have checked the release note of the last firmware “Melody 7.3”.
It was released on December 2018.
And the release date of iOS 13 was September 2019.
Since this module has been end of life for 3 years, I don’t think there will be any new firmware release.

https://source.sierrawireless.com/resources/airprime/software/bc127-firmware/#sthash.BVIs5kBr.Nut9ZAm6.dpbs