Voice over IP network architecture

1 . A next generation public telephone network comprising at least two network domains, each of said network domains comprising a Softswitch for provisioning connections for packetized transport of user sessions within the corresponding network domain, wherein said at least two network domains are interconnected using at least one Session Border Controller acting as packet-to-packet gateway between said at least two network domains,

wherein

an interconnection network comprising an number of Session Border Controllers, wherein at least a first of said Session Border Controllers is connected to a first of said at least two network domains and at least a second of said Session Border Controllers is connected to a second of said at least two network domains, said interconnection network further comprising a dedicated Softswitch for provisioning connections between selected ones of said Session Border Controllers.

2 . A next generation public telephone network according to claim 1 , wherein said dedicated Softswitch is configured as default Softswitch for sessions between subscribers, who are located in different network domains.

3 . A next generation public telephone network according to claim 1 , wherein said dedicated Softswitch of said interconnection network comprises an intelligent database storing routing data taking into account least-cost-routing, congestion control, short-cut finding, constraints of network resources, bandwidth availability and/or bandwidth costs.

4 . A next generation public telephone network according to claim 1 , wherein said dedicated Softswitch of said interconnection network is adapted to support at least one of the following functions:

Signaling protocol translation and interworking,

Message scrubbing for end-user identity and address hiding,

Topology and infrastructure hiding,

Authentication Authorization Accounting,

Firewall function,

Privacy function,

Session based routing,

Load related services including sharing and balancing,

DSP service control,

Call statistics maintenance,

Support for lawful intercept, and

DOS protection.

5 . A next generation public telephone network according to claim 1 , wherein said first and second Session Border Controllers of said interconnection network is adapted to support at least one of the following functions:

Bandwidth allocation and CAC functions,

Policing and marking,

Firewall function,

Network Address and Port Translation and NAT/FW traversal,

DSP services,

Quality and SLA monitoring,

Support lawful interception, and

DOS protection.

6 . A method of establishing a call from a calling subscriber to a called subscriber over at least two network domains of a next generation public telephone network, wherein said calling subscriber is located in a first of said at least two network domains and wherein said called subscriber is located in a second of said at least two network domains, said method comprising the steps of:

sending signaling information from said calling subscriber to a first Softswitch assigned to said first network domain,

provisioning a connection from said calling subscriber through said first network domain to a first Session Boarder Controller under control of said first Softswitch,

transferring signaling information from said first Softswitch to a second Softswitch,

provisioning a connection from said first Session Boarder Controller to a second Session Boarder Controller under control of said second Softswitch,

transferring signaling information from said second Softswitch to a third Softswitch assigned to said second network domain, and

provisioning a connection though said second network domain from said a second Session Boarder Controller to said called subscriber under control of said third Softswitch.