Abstract: An anti-CLI spoofing procedure controls access of a mobile communication device to a service on a communication network via a connection from outside the network. The device issues a unique identifier for identifying the device to the service. If the identifier is received from outside the network and over a secure signaling channel, a first time stamp is stored in a memory, representative of a first time of receipt of the identifier. The connection is set up and then a second time stamp is generated representative of a second time at which the connection is established to a node on the network. A first instruction is issued to establish unconditional access to the service if a time difference between the time stamps falls within a predetermined time window. A second instruction is issued to grant conditional access to the service if the time difference falls outside the predetermined window.

Abstract: An anti-CLI spoofing procedure controls access of a mobile communication device to a service on a communication network via a connection from outside the network. The device issues a unique identifier for identifying the device to the service. If the identifier is received from outside the network and over a secure signaling channel, a first time stamp is stored in a memory, representative of a first time of receipt of the identifier. The connection is set up and then a second time stamp is generated representative of a second time at which the connection is established to a node on the network. A first instruction is issued to establish unconditional access to the service if a time difference between the time stamps falls within a predetermined time window. A second instruction is issued to grant conditional access to the service if the time difference falls outside the predetermined window.