contact the dev of the app and see if you can get a list of tested devices.
unpair and try "phone only" pairing.
1. Turn on the headset and press the Phone Button for 5 seconds
until the LED flashes red and blue alternately and you hear multiple
2. Within 2 seconds, tap the Phone Button again, then the LED turns
to blue flashing and the beeps turn to multiple mid-tone beeps. You
will hear a voice prompt saying “Phone selective pairing”.
3. Search for Bluetooth devices on your smartphone. Select the Sena
SMH5 in the list of devices detected on your phone.
4. Enter 0000 for the PIN. Some smart phones may not ask for PIN.
make double sure the mic is connected properly and in the correct port.
another possibility is that the phone is not properly recognizing the button that is used for making calls.
difficult to diagnose over the internet.
if this product is portable, take it into a local shop and pair it with another phone, or if you have a friend who has a mobile phone, test with theirs. if you have an old phone lying around, test it with that.
if you have access to wired headphones (or wireless) with a mic, connect those and test to see if the voice call function works properly on the phone.
ASSuming you are not rooted and you are running the latest stock firmware, there is not much else to troubleshoot. being that your device is form a different country, there could be subtle software differences from US models that could also be causing an issue.
again, contact the company and see if you can get some official info on a list of compatible devices....