Patent ID: 9276969
Filing Date: 2016-03-01
CPC Classification: H04L

Claim Text:
1. A method for determining whether a SIP session has been established, the method comprising: attempting to initiate a communication session between a first end terminal and a second end terminal, between which a communication session is not already in progress, by transmitting one or more messages toward the second end terminal; starting a first timer at a first network element in a network upon transmitting the one or more messages, the first timer being configured to expire after a first predetermined time period if a first return message to the one or more messages is not received; starting a second timer at a second network element in the network upon transmission of the one or more messages, the second timer being configured to expire after a second predetermined time period if a second return message to the one or more messages is not received; starting a third timer at a third network element in the network upon receipt of the first return message, the third timer being configured to expire after a third predetermined time period if a third return message to the one or more messages is not received; transmitting one or more instructions upon expiration of the first, second, or third timers, the instructions indicating that the communication session between the first end terminal and the second end terminal has not been established; and taking one or more actions based at least in part on the one or more instructions, wherein the one or more actions include informing network elements in the network that the second end terminal is unavailable and/or not functioning.