Subscribe to ANCS on Android

Based on the services listed here, I'm trying to subscribe to a service from an Android device, but can't get the solicitation part working. Tried to advertise using 7905F431-B5CE-4E99-A40F-4B1E122D00D0 but the peripheral is not showing up on the iPhone's bluetooth devices list. Also played with (LE)scan and filters to discover the ANCS server without luck. Any hint?

edit: code

BleService.java

public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic,
                                          boolean enabled) {
    Log.d(TAG, "setCharacteristicNotification");
    if (mBluetoothAdapter == null || mBluetoothGatt == null) {
        Log.w(TAG, "BluetoothAdapter not initialized");
        return;
    }
    mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);
    BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString(SampleGattAttributes.DESCRIPTOR));
    descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
    mBluetoothGatt.writeDescriptor(descriptor)
}

@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
    if (status == BluetoothGatt.GATT_SUCCESS) {
        broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
    }
}

SampleGattAttributes.java

public class SampleGattAttributes {
    public static String ANCS_SERVICE = "7905F431-B5CE-4E99-A40F-4B1E122D00D0";
    public static String NOTIFICATION_SOURCE = "9FBF120D-6301-42D9-8C58-25E699A21DBD";
    public static String DATA_CONTROL = "22EAC6E9-24D6-4BB5-BE44-B36ACE7C7BFB";
    public static String DESCRIPTOR = "00002902-0000-1000-8000-00805f9b34fb";
}

MainActivity.java

private void displayServices(List<BluetoothGattService> services) {
    for (BluetoothGattService service : services) {
        if (service.getUuid().compareTo(UUID.fromString(ANCS_SERVICE)) == 0) {
            for (BluetoothGattCharacteristic characteristic : service.getCharacteristics()) {
                Log.d(TAG, "charac: " + characteristic.getUuid());
                for (BluetoothGattDescriptor descriptor : characteristic.getDescriptors()) {
                    Log.d(TAG, "desc: " + descriptor.getUuid());
                }
                if (characteristic.getUuid().compareTo(UUID.fromString(NOTIFICATION_SOURCE)) == 0) {
                    bleService.setCharacteristicNotification(characteristic, true);
                }
            }
        }
    }
}

private final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();
        if (BleService.ACTION_GATT_SERVICES_DISCOVERED.equals(action)) {
            displayServices(bleService.getSupportedGattServices());
        }
    }
};

update: I'm able to find the services and characteristics after connecting to a service advertised on the iPhone. However, subscribing to notifications doesn't trigger onCharacteristicChanged upon receiving a notification on the iPhone.

update2: all the write descriptor.setValue calls are successful, and run in sequence.

update3: used part of the code from this sample.

update4: test devices: Nexus 5X Android 6.0.1; iPhone 6S+ iOS 10.3.1

update5: BT logs

write request

write response

Oh I had a similar issue, make sure you don't use Local Notifications when testing on iOS as those won't be propagated through ANCS. You need real push notifications for whatever reason.