Method and system for intersystem wireless communications session hand-off

A method of handing off a communication session with a mobile station when the mobile station is engaging in the communication session via a first access system and then registers in a second access system, wherein the first access system provides access to a transport network for both the first access system and the second access system, wherein the first access system includes a first access node, wherein the first access node is communicatively linked to a switch that in turn is communicatively linked to the transport network, wherein the second access system includes a second access node, wherein when the mobile station is in the first access system the mobile station communicates with a first access node according to a first protocol, and wherein when the mobile station is in the second access system the mobile station communicates with a second access node according to a second protocol different than the first protocol, the method comprising:

• after registration of the mobile station in the second access system, carrying the communication session between the mobile station and the second access node according to the second protocol over the first protocol;
• instructing the switch to route incoming data of the communication session to the second access system, for transmission in turn to the mobile station, wherein the incoming data of the communication session passes from the first access system to the second access system through a gateway, wherein the second access node is communicatively linked with the gateway and wherein the gateway is communicatively linked to the switch;
• the switch sending the incoming data destined for the mobile station to the gateway;
• the gateway receiving the incoming data destined for the mobile station:
• the gateway encoding the incoming data according to the first protocol so as to produce incoming first-protocol-encoded data;
• the gateway encapsulating the incoming first-protocol-encoded data in headers of the second protocol so as to produce incoming second-protocol-encapsulated first-protocol-encoded data;
• and
• the gateway sending the incoming second-protocol-encapsulated first-protocol-encoded data to the second access system for transmission in turn to the mobile station.

A method of handing off a communication session to a mobile station via a first access system when the mobile station is engaging in the communication session via a second access system and then registers in the first access system, wherein the first access system and second access system both provide access to a common transport network, wherein the first access system includes a first access node, wherein the second access system includes a second access node, wherein the first access node and second access node are both communicatively linked with a common gateway to the common transport network, wherein when the mobile station is in the first access system the mobile station communicates with a first access node according to a first protocol, wherein when the mobile station is in the second access system, the mobile station communicates with a second access node according to the second protocol over a first protocol, and wherein the first protocol is different than the second protocol, the method comprising:

• after registration of the mobile station in the first access system, carrying the communication session between the mobile station and the first access node according to the first protocol;
• instructing the common gateway to route incoming first-protocol-encoded data of the communication session to the first access system for transmission in turn to the mobile station;
• the common gateway receiving incoming second-protocol-encapsulated first-protocol-encoded data destined for the mobile station;
• the common gateway stripping headers of the second protocol from the incoming second-protocol-encapsulated first-protocol-encoded data so as to uncover first-protocol-encoded data;
• and
• the common gateway sending the incoming first-protocol-encoded data to the first access system for transmission in turn to the mobile station.

A method of handing off a communication session to a mobile station via a first access system when the mobile station is engaging in the communication session via a second access system and then registers in the first access system, wherein the first access system provides access to a transport network for both the first access system and the second access system, wherein the first access system includes a first access node, wherein the second access system includes a second access node, wherein when the mobile station is in the first access system the mobile station communicates with a first access node according to a first protocol, wherein when the mobile station is in the second access system the mobile station communicates with a second access node according to the second protocol over the first protocol, and wherein the first protocol is different protocol that the second protocol, the method comprising:

• after registration of the mobile station in the first access system, carrying the communication session between the mobile station and the first access node according to the first protocol, wherein incoming second-protocol encapsulated first-protocol encoded data of the communication session passes from the second access system to the first access system through a gateway;
• instructing the gateway to strip headers of the second-protocol from the incoming second-protocol encapsulated first-protocol-encoded data of the communication session so as to uncover incoming first-protocol-encoded data;
• and
• the gateway routing the incoming first-protocol-encoded data to the first access system, for transmission in turn to the mobile station.