Phone Number = Telephony Symbol
FPhone
Number Is a Universal Symbol
Has
Multiple Implementations
Rotary Dialer, Touch-Tone Keypad
Pulse-Dialed, DTMF, etc.
BCD-encoded, ASCII-string, Binary, etc.
Overloaded
for Multiple Meanings
Caller-ID -- Who Is Calling, NOT What Device
800, 500-like Services, 500-CALL-GTE
Black-Box
Processing by the Network
Has Universal
Meaning to the User