7. The arrangement of claim 5 wherein: the defining means comprise means for storing definitions of individual symbol strings of the network numbering plan, each definition including an identification of the string type of the defined string.
7. The arrangement of claim 5 wherein: the defining means comprise means for storing definitions of individual symbol strings of the network numbering plan, each definition including an identification of the string type of the defined string. 8. The arrangement of claim 7 wherein: each symbol string's definition includes an indication of a length of the defined symbol string.