Emergency Service Query Key. One of the P‐ANIs used for VSP routing over the peering network. An ESQK identifies a

call instance at a VPC, and is associated with a particular SR/ESN combination. The ESQK is used by the SR as a key to the

selective router data associated with the call. The ESQK is delivered by the SR to the PSAP as the calling number/ANI for

the call, and is used by the PSAP to request ALI information for the call. The ALSO database includes the ESQK in

locations requests sent to the VPC. The ESQK is used by the VPC as a key to look up the location object and other call

information associated with an emergency call instance. The ESQK is a 10‐digit NANP number.