No alert tone heard if network does not play it in-band

[Martti Piirainen]

Test case:
 - Dial a voice call
 - Call starts ringing at the other end
 - Expecting to hear an alerting tone in my earpiece
 - But there is only silence

This is a rare but valid "feature" in some commercial networks, for example Bouygues Telecom, France. The in-band audio connection is sometimes not yet set up in the alerting phase.

The relevant technical specification piece, from 3GPP TS 24.008 sect. 5.2.1.5 "Alerting": "an alerting indication should be given to the user. If the mobile station has not attached the user connection then the mobile station shall internally generate an alerting indication".

The Android RIL API supports this feature via notification "RIL_UNSOL_RINGBACK_TONE", http://androidxref.com/4.2.2_r1/xref/hardware/ril/include/telephony/ril.h#3717 . Ubuntu should listen to this notification and generate the alerting tone appropriately.

[Martti Piirainen (piiramar)]

The oFono part has already been implemented in the Nemo Mobile project's fork: https://github.com/nemomobile-packages/ofono/pull/214 . I merged and adapted it, see private branch https://github.com/marttipiirainen/ofono-1/tree/ringback_tone .

I tested this new oFono API using the 'test-voicecallagent' Python script. In the Sonera/Finland network, I get an in-band ringing tone, and nothing is notified to the agent. Using an Anritsu network simulator, I do not get an in-band tone from the network, so (the modem and the RIL API and) the oFono API notifies when a locally generated ringing tone should be started and stopped.

  {VoiceCall} [/ril_0/voicecall01] State = alerting
  Agent got playTone notification: 1
  Agent got playTone notification: 0
  {VoiceCall} [/ril_0/voicecall01] State = active

The attached file contains test script output and oFono logs from both cases (using the abovementioned private branch).

[Martti Piirainen (piiramar)]

Forgot to add: Tests in comment #1 were made with mako HW and on top of Ubuntu image 154.

[Martti Piirainen (piiramar)]

Not being worked on, un-assigning.

[Tony Espy (awe)]

Sometimes when using a SIM card that's inactive, the dialer-app creates a call that is in "dialing" state and just hangs. I wonder if should be generating any tone at all in this situation?

[Jussi Kangas (jkangas)]

If the phone has no SIM card or card connection is otherwise "inactive", only call that could happen in that situation should be a emergency call. I think it would be very comforting feature for customer to hear tone in the line in that situation.

[Jussi Kangas (jkangas)]

Ofono change: https://github.com/rilmodem/ofono/pull/117

[Tony Espy (awe)]

Moved back to ofono task back to Confirmed as this is not actively being worked on...