Base station subsystem and method for handling an increase in traffic volume that overloads a terrestrial link in an internet protocol network

A cellular communications system capable of handling an overload situation within a terrestrial link, said cellular communications system comprising:

• a transmitter for communicating at least one packet based call over an air interface with a mobile phone;
• an interface unit;
• an Internet Protocol network for passing the at least one packet based call over the terrestrial link between said transmitter and said interface unit;
• and
• said transmitter and said interface unit each including an end-point for measuring a delay in passing said at least one packet based call through the terrestrial link in said Internet Protocol network and when the delay as measured by one of the end-points exceeds a predetermined value, then downgrading a transmission rate associated with said at least one packet based call to handle the overload situation.

A method for handling an overload situation within an Internet Protocol network included within a base station subsystem of a cellular communications system, said method comprising the steps of:

• measuring a delay in passing at least one call through a terrestrial link between a transmitter and an interface unit of said Internet Protocol network at an endpoint in either the transmitter or the interface unit;
• determining at the endpoint when the measured delay exceeds a predetermined value;
• and
• downgrading at the endpoint, in response to an affirmative determination, a transmission rate associated with said at least one call to address the overload situation resulting from the delay within said Internet Protocol network.