IMS network access using legacy devices

A method of operating a communication network for providing a legacy device access to an IP Multimedia Subsystem (IMS) network, the method comprising:

• receiving a call from a calling party using a legacy device to a called party into a switching system, wherein the switching system is within a circuit-switched legacy network and outside of the IMS network;
• determining where to route the call based on whether the calling party is an IMS subscriber using a legacy device
• routing the signaling for the call from the switching system to the IMS network if the calling party is an IMS subscriber using a legacy device so that the calling party is able to access IMS services through the legacy device even though the legacy device does not perform IMS registration;
• and
• routing the signaling for the call from the switching system to a non-IMS network if the calling party is not an IMS subscriber using a legacy device.

A communication network, comprising:

• a calling party IP Multimedia Subsystem (IMS) network;
• a subscriber database that stores identities of IMS subscribers that use legacy devices which are not able to register with the IMS network;
• and
• a switching system that serves a legacy device which is not able to register with the calling party IMS network, wherein the switching system is within a circuit-switched legacy network and outside of the IMS network;
• the switching system receives a call from a calling party using the legacy device to a called party, accesses the subscriber database based on a calling party identifier to determine where to route the call based on whether the calling party is an IMS subscriber using a legacy device, routes signaling for the call to the calling party IMS network if the calling party is an IMS subscriber using a legacy device so that the calling party is able to access IMS services even though the legacy device does not perform IMS registration, and routes the signaling for the call to a non-IMS network if the calling party is not an IMS subscriber;
• the calling party IMS network receives the call, determines if the called party is an IMS subscriber, and routes the signaling for the call to the non-IMS network if the called party is not an IMS subscriber.