User Story

Intercloud provides OTT service to mobile users using AudioCodes MobilityPlus within Bangladesh. When the user is abroad and does not have or use roaming, they may still use the app over WiFi. It is required to notify user's MNO about app's SIP registration, so MNO would send incoming calls for this user to PortaSwitch, which will deliver the call to the app (a VoIP call instead of a GSM one).

Use Cases

Use case #1: Incoming calls to mobile users with MobilityPlus app

Roles: administrator, user, mobile caller

Preconditions: the user has a smartphone with MobilityPlus installed and configured with phone number 8801234567

Use scenario #1.1: Incoming GSM call while being in Bangladesh

• User starts the app and it registers in PortaSwitch

• Another mobile user makes a call to 8801234567
• The call is delivered to the user's mobile phone (via GSM network)

Use scenario #1.2: Incoming GSM call while being abroad

• User connects to WiFi, starts the app and it registers in PortaSwitch

• PortaSwitch forwards that registration to external gateway, which notifies user's MNO
• Another mobile user makes a call to 8801234567
• MNO sends the call to PortaSwitch
• The call is delivered to the app

Other requirements / constraints

Originally the idea was to use DNS that would dynamically resolve the same FQDN to different IPs based on source IP of registration (if the user is in Bangladesh, send registrations to one IP; when the user is abroad, send registrations to another IP) and to run 2 PortaSIP servers on those IPs. However, having this forwarding feature per server/IP does not make sense in the context of SIP cluster. Any better suggestions on how to distinguish the domestic/abroad scenarios are welcome.