Patent ID: 7961852

Claim:
A method of sending at least one request to a domain name server from a requesting machine, said domain name server being an E.164.arpa telephone number domain name server and each name being determined from an E.164 format destination telephone number contained in said request, wherein a prior test of the validity of the destination telephone number of the request is executed automatically and locally to the requesting machine relative to a telephone number database local to the requesting machine to forward the request from the requesting machine to the domain name server only if its destination telephone number passes said test; wherein at least one numbering plan is stored in the telephone number database local to the requesting machine, the numbering plan or each numbering plan comprising at least one block of telephone numbers, and said test includes a step of determining whether the destination telephone number of the request belongs to a block of numbers of the numbering plan, the destination telephone number of the request failing said test if a result of the determination step is negative; and wherein separate blocks of telephone numbers associated with respective prescribed characteristics of numbers in the block are stored in the telephone number database local to the requesting machine and said determination step further comprises a step of determining to which block of telephone numbers in the telephone number database local to the requesting machine the destination telephone number of the request belongs, and if it is determined that the destination telephone number of the request belongs to a block of the numbering plan the characteristics associated with the block thus determined are read in the telephone number database local to the requesting machine, it is verified whether the destination telephone number of the request conforms to the characteristics thus read, and the request is forwarded from the requesting machine to the domain name server only if the verification result is a positive result.