Use cases

User Story:

1) Customer's PSTN to SIP gateways are overloaded, they could not generate RBT after receiving 180 Ringing. Thus, there are situations when caller from PSTN hears silence until the call is picked up by the callee. This decreases ASR and results in bad customer experience. Customers will be happier if RBT is generated on PortaSwitch.

2) Users with Auto Attendant are not satisfied when Carrier Announcements (media received in 183 Session Progress) are not relayed.
When the call goes through Auto-Attendant, media received from callee after 180 Ringing or 183 Session Progress is not relayed to the calling party. Calling party hears MOH. This creates issues in 2 frequent cases:

• Call is transferred from AA to a mobile number. Mobile Carrier announces in 183 Session Progress "Subscriber is not available, you may leave a voicemail". After the announcement, the call is connected and the caller hear "Beep" and silence. Caller can hardly guess that he is talking to a voicemail.
• Call is transferred from AA to a mobile number. Mobile Carrier announces in 183 Session Progress "Subscriber is not available, please call again later". Caller hears nothing (or MOH).

It would be nice if we can optionally enable passing Carrier Announcements in AA settings, so that Carrier Announcement will be relayed to the caller if AA owner finds it necessary.

Use case #1: Administrator enables Ring-Back Tone generation by PortaSwitch

Roles: Administrator, system

Preconditions:  there is a "Ring" file with the RBT that should be played.

Use scenario #1.1: Administrator configures RBT generation

Scenario:

• Administrator enables RBT generation when 18x is received without SDP;

• Administrator enables RBT generation when 18x is received with SDP, but there is no RTP sent by the called party;

• Administrator uploads a "Ring" file that will be played as RBT;

• The system accepts these changes.

Use case #2: Generation of Ring-Back Tone on PortaSwitch side

Roles: End-users, PortaSwitch, Gateway with IP 1.1.1.1

Preconditions: 1112223333 number is in the system, 790211122233 is an external mobile number.

Administrator configured early media detection interval = 3 seconds. If there is no early media for 3 seconds, PortaSwitch generates local Ring-Back Tone.

• Ring-Back Tone generation is enabled

• End-user with the number 1112223333 makes outgoing call to 790211122233

• Call goes via SIP Instance 1 to the connection 1.1.1.1.

• PortaSwitch receives 180 Ringing ( or 183 Session Progress) from 1.1.1.1 without SDP.

• PortaSwitch generates Ring Back Tone with "Ring" file and sends it to caller 1112223333.
• Caller 1112223333 hears music from the "Ring" file.

• Owner of 790211122233 picks up the call and they are talking.

• There is incoming call from 790211122233 number to 1112223333;

• The 1112223333 is out of the office, the call is forwarded to 790911122244;

• Call goes via the connection 1.1.1.1.

• PortaSwitch receives 180 Ringing ( or 183 Session Progress ) without SDP from 1.1.1.1.

• PortaSwitch generates Ring Back Tone with "Ring" file and sends it to caller 790211122233.
• Caller 790211122233 hears music from the "Ring" file.

• Owner of 790211122244 picks up the call and they are talking.

• End-user with the number 1112223333 makes outgoing call to 790211122233

• Call goes via the connection 1.1.1.1.

• PortaSwitch receives 180 Ringing (or Session Progress) with SDP from 1.1.1.1

• Gateway 1.1.1.1 sends RTP with early media
• PortaSwitch relays early media

• Caller hears early media.

Use scenario #2.4: 180 Ringing (or 183 Session Progress) comes with SDP, RTP is missing - PortaSwitch generates RBT

• End-user with the number 1112223333 makes outgoing call to 790211122233

• Call goes via the connection 1.1.1.1.

• PortaSwitch receives 180 Ringing (183 Session Progress) with SDP from 1.1.1.1

• Gateway 1.1.1.1 does not send any RTP with early media.
• PortaSwitch detects that there is no RTP for 3 seconds and starts playing Ring-Back Tone from the "Ring" file.

• Caller hears RBT from the "Ring" file .

Use scenario #2.5: Switchover from generated RBT to relayed Carrier Announcement

• End-user with the number 1112223333 makes outgoing call to 790211122233

• Call goes via the connection 1.1.1.1.

• PortaSwitch receives 180 Ringing (183 Session Progress) with SDP from 1.1.1.1

• Gateway 1.1.1.1 does not send any RTP with early media.
• PortaSwitch detects that there is no RTP for 3 seconds and starts playing Ring-Back Tone from the "Ring" file.

• Caller hears RBT from the "Ring" file .

• In 10 seconds PortaSwitch receives RTP with Carrier Announcement.
• PortaSwitch stops RBT generation, starts RTP relay.
• Caller hears Carrier Announcement.

Use case #3: Call goes through AA, Carrier Announcements are relayed

Roles: End-users, PortaSwitch, Administrator

Preconditions:

At the moment on customer's installation, different SIP instances have different MOH configurations:
 - MOH_transfer_mode=0(no MOH),
 - MOH_transfer_mode=2(transferor's MOH, if present),
 - MOH_transfer_mode=3(transferor's MOH, if present, else moh_1).

In these scenarios we will consider that MOH is not configured:

• MOH_transfer_mode=0 or
  
• MOH_transfer_mode=2 and MOH is not configured by the end-user.

790211122244 is an external mobile number;

790211122255 is an account in the system with AA. MOH is not configured on account. AA settings: action 1- forward to ext. 444 (account 000999444). Account 000999444 has forward to mobile number 790211122233 on no answer

There is connection 1.1.1.1 that passes calls to 7 destination.

Administrator configured early media detection interval = 3 seconds. If there is no early media for 3 seconds, PortaSwitch generates local Ring-Back Tone.

Use scenario #3.1: Relay Early Media when the call goes through AA;

•  790211122244 calls 790211122255 hears the prompt and enters 1;
• The call is forwarded to 000999444. The phone is ringing;
• PortaSwitch receives 180 Ringing (or 183 Session Progress) with SDP;
• Early media with RBT is sent by the phone;
• PortaSwitch relays early media to 790211122244 ;
• 000999444 does not pick up the phone; the call is forwarded to 790211122233; 790211122233 starts ringing;
• PortaSwitch receives 180 Ringing (or 183 Session Progress) with SDP;
• Mobile operator plays Custom Ringback Tone - Madonna's song via early media;
• PortaSwitch relays early media;
• 790211122233 picks up the phone and talks to 790211122244.

Expected result: Caller first hears RBT generated by IP Phone (of account 000999444), then hears Madonna's song, then 790211122233 answers.

Use scenario #3.2: RBT is generated by PortaSwitch on receiving 180/183 without SDP;

•  790211122244 calls 790211122255;
• 790211122244  hears the AA prompt and enters 1;
• The call is forwarded to 000999444. The phone is ringing;
• PortaSwitch receives 180 Ringing (or 183 Session Progress) without SDP, generates Ring Back Tone with "Ring" file;
• 790211122244 hears RBT from the file "Ring";
• 000999444 does not pick up the phone; the call is forwarded to 790211122233; 790211122233 starts ringing;
• PortaSwitch receives 180 Ringing without SDP, generates Ring Back Tone with "Ring" file and sends it to caller 790211122244;
• 790211122244 hears RBT from the file "Ring";
• 790211122233 picks up the phone and they talk.

Expected result: Caller first hears RBT by PortaSwitch for a call to 000999444, then a short pause, then RBT by PortaSwitch for a call to 790211122233.

Use scenario #3.3: RBT is generated by PortaSwitch when RTP with Early Media is missing;

•  790211122244 calls 790211122255;
• 790211122244  hears the AA prompt and enters 1;
• The call is forwarded to 000999444. The phone is ringing;
• PortaSwitch receives 180 Ringing (or 183 Session Progress) with SDP;
• PortaSwitch detects that there is no RTP stream from 000999444 after 3 seconds.
• PortaSwitch plays RBT from the file "Ring";
• 000999444 does not pick up the phone; the call is forwarded to 790211122233; 790211122233 starts ringing;
• PortaSwitch receives 180 Ringing (or 183 Session Progress) with SDP;
• In 3 seconds PortaSwitch detects that there was no RTP to relay, so PortaSwitch starts RBT generation
• 790211122244 hears RBT from the file "Ring";
• 790211122233 picks up the phone and they talk.

Expected result: Caller first hears silence for 3 seconds, then RBT by PortaSwitch for a call to 000999444, then silence for 3-4 seconds, then RBT by PortaSwitch for a call to 790211122233.