CAMEL based Call Transfer for IN-VPN in GSM or UMTS Networks (CCT)
Original Publication Date: 2002-Jun-01
Included in the Prior Art Database: 2003-Jul-23
Georg Reininghaus: AUTHOR [+2]
In order to enable a GSM or UMTS subscriber (B- Party) to use her mobile phone to connect a calling party (A-Party) to another party (C-Party) there is a core network solution called ETC (Explicit Call transfer) that is specified by the ETSI (European Technical Standards Institute) standard. However this solution does not work together with IN (Intelli- gent Network) services.
CAMEL based Call Transfer forIN-VPN in GSM or UMTS Net-works (CCT)
Information / Kommunikation
Idee: Georg Reininghaus, A-Wien;
Andreas Zöchling, A-Wien
In order to enable a GSM or UMTS subscriber (B-Party) to use her mobile phone to connect a callingparty (A-Party) to another party (C-Party) there is acore network solution called ETC (Explicit Calltransfer) that is specified by the ETSI (EuropeanTechnical Standards Institute) standard. Howeverthis solution does not work together with IN (Intelli-gent Network) services.
A CAMEL (Customised Applications for Mobilenetwork Enhanced Logic) based Call Transfer forIN-VPN (IN-Virtual Private Network) is proposed inorder to establish a connection between A- and C-Party. Prior to transfer a connection shall have beenestablished on the call between A and B. Using thesupplementary service “Call Hold” the served sub-scriber (B-Party) sets up a second connection to theC-Party to ensure that the C-Party is reachable. Thecall (transfer) between A and C is established whenthe connections B to C and A to B are released by theB-party.
Following preconditions have to be satisfied beforeinvoking CCT (Camel based Call Transfer):
• The VPN service has to check the chargingscenario and call permissions after transfer. If soVPN has to provide corresponding charging rec-ords, otherwise the transfer request shall be re-jected by VPN.
• The served subscriber (B-party) has to be pro-vided with CSI information for VPN-call as wellas USSD.
• The call A to B shall be in the state [active; held]and the call B to C in the state [active; idle].
• No other originating or terminating call exists atthe access of the B-party. Forwarded calls arenot relevant.
The served subscriber may initiate CCT as follows:
1. The Mobile Station (MS) activates the service bysending a USSD request towards the networkindicating the Call Transfer request. The net-work does not change the call state of the con-nection A- to B-Party or B- to C-Party when re-ceiving the request.
2. The network normally accepts the USSD requestand forwards it to the IN-VPN service (viaMSC/VLR, HLR and CSE).
3. On receipt the IN-VPN service provides fol-lowing checks:
- The permission of the B-party is checkedbased on the received MSISDN (MobileSubscriber ISDN number) against black-/whitelists.
- The call scenario is checked (one call active,one held).
- The charging scenarios are checked. Nor-mally B- and C-party must be VPN mem-bers.
4. If all checks passed, CCT is activated and aconfirmation with USSD response is sent to-wards the B-Party MS. Otherwise the request isrejected with a USSD response. Note that thestate of the calls is not changed at that time.
5. To invoke CCT the served subscriber requestsrelease of her calls to A and C.
- On receipt the network terminates the call to
- Subsequently the...