1. A method comprising: a call router system associating a first Uniform Resource Identifier (URI) of an external first application server with a first telephony endpoint of the call router system; the call router system providing information of a first telephony voice session of the first telephony endpoint to the first application server via the first URI; the call router system receiving a first telephony instruction from the first application server responsive to the information of the first telephony voice session; and the call router system executing a first action for the first telephony voice session based on the first telephony instruction.