Telephony signalling element

1. A telephony signalling element comprising:

a signalling processing function comprising:

instantiations of a transaction handling function;

instantiations of an admission control function; and

instantiations of an access control function;

and a session datastore function comprising:

instantiations of a registration data store, wherein instantiations of the registration data store comprise a distributed data store in which subscriber registration session state data is stored; and

one or more instantiations of a dialog data store, wherein the instantiations of the dialog data store comprise a distributed data store in which dialog and call state data is stored,

wherein instantiations of the signalling processing function are separate from instantiations of the session datastore function, and wherein instantiations of the signalling processing function are able to communicate with instantiations of the session datastore function via one or more interfaces.

2. A telephony signalling element according to claim 1 , wherein the number of instantiations of the transaction handling function, admission control function, and access control function in the signalling processing function are independently scalable of each other.

3. A telephony signalling element according to claim 1 , wherein the number of instantiations of the registration data store and dialog data store in the session datastore function are independently scalable of each other.

4. A telephony signalling element according to claim 1 , wherein instantiations in the signalling processing function are independently scalable of instantiations in the session datastore function.

5. A telephony signalling element according to claim 1 , wherein at least one of the instantiations of the signalling processing function is physically separate from one or more instantiations of the session datastore function.

6. A telephony signalling element according to claim 1 , wherein the signalling processing function comprises one or more instantiations of a media session control function.

7. A telephony signalling element according to claim 1 , wherein the signalling processing function comprises one or more instantiations of a connection termination function.

8. A telephony signalling element according to claim 1 , wherein transaction handling function instantiations are configured to process signalling message transactions to completion.

9. A telephony signalling element according to claim 1 , wherein transaction handling function instantiations are configured to access services of one or more of:

connection termination function instantiations,

admission control function instantiations,

media session control function instantiations,

access control function instantiations,

registration data store instantiations, and

dialog data store instantiations.

10. A telephony signalling element according to claim 1 , wherein admission control function instantiations are configured to authorise and rate limit requests based on policy.

11. A telephony signalling element according to claim 1 , wherein access control function instantiations are configured to manage one or more access control lists associated with the telephony signalling element.

12. A telephony signalling element according to claim 1 , wherein each item of data stored in an instantiation of the registration data store is replicated across other instantiations of the registration data store.

13. A telephony signalling element according to claim 1 , wherein each item of data stored in an instantiation of the dialog data store is replicated across other instantiations of the dialog data store.

14. A telephony signalling element according to claim 1 , comprising one or more of:

one or more instantiations of a service discovery function,

one or more instantiations of a diagnostics collection function,

one or more instantiations of a monitoring function,

one or more instantiations of a virtualised network function (VNF) manager,

one or more instantiations of an orchestrator,

one or more instantiations of a load balancer,

one or more instantiations of a licensing service,

one or more instantiations of a denial of service (DoS) protection function,

one or more instantiations of a packet filtering function,

one or more instantiations of a user management function,

one or more instantiations of an authentication, authorisation, and accounting function, and

one or more instantiations of a network probe function.

15. A telephony signalling element according to claim 1 , wherein the telephony signalling element comprises a Session Border Controller (SBC).

16. A telephony signalling element according to claim 1 , wherein the telephony signalling element comprises one or more of:

an Internet Protocol Multimedia Subsystem Proxy-Call Session Control Function (IMS P-CSCF),

an Interconnection Border Control Function (IBCF),

an Emergency-Call Session Control Function (E-CSCF),

an access Session Border Controller (SBC),

an interconnect SBC,

a peering SBC,

a trunking SBC,

a Session Initiation Protocol (SIP) edge proxy,

a SIP Back (B2BUA) and

an Internet Protocol version 4 (IPv4)-Internet Protocol version 6 (IPv6) interworking SBC.

17. A method of operating a telephony signalling element, the method comprising:

providing a signalling processing function comprising:

instantiations of a transaction handling function;

instantiations of an admission control function; and

instantiations of an access control function;

and providing a session datastore function comprising:

instantiations of a registration data store, wherein instantiations of the registration data store comprise a distributed data store in which subscriber registration session state data is stored; and

instantiations of a dialog data store, wherein the instantiations of the dialog data store comprise a distributed data store in which dialog and call state data is stored,

wherein instantiations of the signalling processing function are instantiated separately from instantiations of the session datastore function, and wherein instantiations of the signalling processing function are able to communicate with instantiations of the session datastore function via one or more interfaces.

18. A computer program comprising a set of non-transitory instructions, which, when executed by a computerised device, cause the computerised device to perform a method of operating a telephony signalling element, the method comprising:

providing a signalling processing function comprising:

instantiations of a transaction handling function;

instantiations of an admission control function; and

instantiations of an access control function;

and providing a session datastore function comprising:

instantiations of a registration data store, wherein instantiations of the registration data store comprise a distributed data store in which subscriber registration session state data is stored; and

instantiations of a dialog data store, wherein the instantiations of the dialog data store comprise a distributed data store in which dialog and call state data is stored,

wherein instantiations of the signalling processing function are instantiated separately from instantiations of the session datastore function, and wherein instantiations of the signalling processing function are able to communicate with instantiations of the session datastore function via one or more interfaces.