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. A CAMEL (Customised Applications for Mobile network Enhanced Logic) based Call Transfer for IN-VPN (IN-Virtual Private Network) is proposed in order to establish a connection between A- and C- Party. Prior to transfer a connection shall have been established on the call between A and B. Using the supplementary service “Call Hold” the served sub- scriber (B-Party) sets up a second connection to the C-Party to ensure that the C-Party is reachable. The call (transfer) between A and C is established when the connections B to C and A to B are released by the B-party.
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...