1. SDS Foil no 1 PBX Make your own PBX – solution sketch

2. SDS Foil no 2 First structure Is this sufficient to make a real PBX? system LocalSwitch t[*]:Terminal ua[*]:UserAgt Message router Nameserver

3. SDS Foil no 3 Voice over IP solution system LocalSwitch t[*]:Terminal ua[*]:UserAgtl Message router Nameserver IP network voice

4. SDS Foil no 4 Line switched voice solution system LocalSwitch t[*]:Terminal ua[*]:UserAgtl Message router Nameserver Line switch voice

5. SDS Foil no 5 First step – the a role as specified in the MSC process type UserAgent 1(2) CallTo Idle Alerting Inviting Alerted Request Busy Idle Connect Alerted Connected Busy Connected-a

6. SDS Foil no 6 Second step – adding the b role process type UserAgent 1(2) CallTo Idle Alerting Inviting Alerted Setup Busy Idle Answer Ringing Connect Busy Request Ringing Alerting Connected-b Ringing Connect Alerted Connected Connected-a Ringing Note that addressing is not considered yet Note that disconnection is not shown

7. SDS Foil no 7 Third step – considering signal addressing process type UserAgent 1(2) CallTo(b,ta) Idle Alerting Inviting Alerted Request To b Busy Idle Connect Alerted Connect To ta Busy To ta Connected-a DCL a,b,ta PId;

8. SDS Foil no 8 Fourth step – considering multiple initiatives and busy process type UserAgent 2(2) *(Idle) Request - Busy Note that Busy handling is very simple here Note that CallTo may collide with Request

9. SDS Foil no 9 Remarks What if the b agent is identified by an external name instead of a PId – how to get the b PId then?? What if more intelligent busy treatment is needed? What if the b agent is identified by an external name instead of a PId – how to get the b PId then?? What if more intelligent busy treatment is needed?

10. SDS Foil no 10 Adding allocator and nameserver system LocalSwitch nameserver ua:UserAllo us:UserServ U(*):UserAgent Message Router t[*]:Terminal Note that external names maps to allocators now! Note that we need to: 1) define the behaviour of UserAllo and 2) change the previous UserAgt to become the new UserServer. Note that we may split the UserServer according to roles: Originating (A) and Terminating (B) Note that external names maps to allocators now! Note that we need to: 1) define the behaviour of UserAllo and 2) change the previous UserAgt to become the new UserServer. Note that we may split the UserServer according to roles: Originating (A) and Terminating (B)

11. SDS Foil no 11 Adding the allocators and the nameserver CallTo Request_self MSC Succesful_Outgoing_Call_modified Alerting ReleaseComplete Connected Disconnect a:Terminal a: UserServer b:UserServer Connect b:Terminal Ringing Answer b:UserAllo a:UserAllo Grant_self Request Grant Sieze Free Lookup LookupResult Nameserver

12. SDS Foil no 12 Adding agents for external switches If we have a standard internal interface, we can just add different types of agents! system LocalSwitch nameserver ua:UserAllo us:UserServ U(*):UserAgent Message Router t[*]:Terminal (*): Node Type1 pa:LinkAllo l(l):protokol o(k):OtherAgent

13. SDS Foil no 13 Adding agents for operators If we have a standard internal interface, we can just add different types of agents! system LocalSwitch nameserver ua:UserAllo us:UserServ U(*):UserAgent Message Router t[*]:Terminal (*): Node Type1 pa:LinkAllo l(l):protokol o(k):OtherAgent Oa:OPAllo Os:OpServ O(*):OPAgent ot[*]:Operatorl