voice troubleshooting case debrief-no ringback tone

Problem description:
No ringback tone when calling from PSTN

Explanation:
- if the AS5300 sends a "180 Ringing", the IP phone is expected to play local ringback.
- if the AS5300 sends a "183 Session Progress", then it will cut-through early-media and the ringback will come from the PSTN switch.

Now there can be some scenarios, depending on the PI value that is send in the ISDN messaging, where we have to tweak the AS5300 behavior.

Action Plan:
1.Please capture the following debug while making test calls:
"debug ccsip all" and "debug isdn q931".
2.you may be able to add "no isdn incoming alerting add-PI" under the serial interface in order to get the 180 ringing.Please try it and let me know how it goes.
3.You can play around with the PI settings / mappings on the 5300:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t5/dt4t323.htm
1- Please check the doc below.It explains well how to fix this problems when ringback tone is not heard:
http://www.ciscotaccc.com/kaidara-advisor/voice/showcase?case=K78361372

Try to configure the two commands mentioned in the article above

progress_ind alert enable 8
progress_ind setup enable 3

under the POTS dial peer towards the PSTN .

2- We can generate the ring back tone locally in the GW by typing the command
'tone ringback alert-no-pi'
under the SIP dial peer that the call comes in on the GW.

Please add this hidden command:
progress_ind alert strip 2

" progress_ind setup enable 3":
The outbound call should include a PI of 3, indicating that the originating device is non-ISDN, and that ringback should be provided inband by the PSTN. The progress_ind setup enable 3 command ensures this behavior.
"progress_ind alert enable 8":
The returning alert message from the PSTN should then include a PI of 8, indicating to the originating gateway that inband information (in this case ringback tone) follows, and that the call should be cut through in the reverse direction so that this information can be heard at the origin.
If the returning alert message does not include a PI of 8, the progress_ind alert enable 8 command can be inserted into the Plain Old Telephone Service (POTS) dial peer and will make the originating Cisco IOS gateway cut through the voice path, as if it received an alert with a PI of 8 from the PSTN.
"tone ringback alert-no-pi "
The gateway is also capable of providing ringback tone on the IP call leg if necessary. The tone ringback alert-no-pi command will enable this functionality, and should be used only if the PSTN switch cannot provide inband ringback tone.