Switching to VoIP

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E.164 Address Scheme

E.164 is a convention for assigning telephone numbers to endpoints on a VoIP net-

work. It’s also the global convention for numbering of country codes, and is backward-

compatible with older ITU recommendations for numbering. The phone numbers you

dial on your analog phone when you call the pizza place and the barber shop—those

are E.164-compliant numbers. Unlike older recommendations, however, E.164 allows

endpoints on a VoIP network to dynamically register their E.164 address (number)

from a list of available numbers stored in a database on the gatekeeper.

This database is an administrator-maintained list of Ethernet MAC hardware

addresses, each of which corresponds to one or more assigned E.164 addresses. In this

fashion, the administrator controls which endpoints are able to use a given E.164

address. In effect, the MAC address becomes the key to the endpoint’s phone number,

which makes telephone moves easier than they are with traditional telephony: no mat-

ter which port the phone moves to on the network, its E.164 address always follows.

Unfortunately, there are drawbacks to using the MAC address as a key for the E.164

address. First, MAC addresses follow a somewhat esoteric hexadecimal convention

that isn’t user friendly. Unless you’re a serious ...