Hello Ian,

> In practice, telephone numbers are a scarce public resource 
> being managed in
> the public interest.  Increasing the number of digits in a 
> telephone number
> has significant network planning, configuration, temporal and resource
> implications.  In practice, there isn't anywhere near the 
> flexibility in
> telephone number availability, that there is in domain name 
> availability.

Yes - note there is an equivalent problem in the Internet in terms of the IP
address range.
There is a new standard which incorporates more "digits" - but it is
difficult to deploy due to impact on network planning, configuration,
equipment compatibilities etc etc.

The domain name is an identifier that can refer to a physical IP address.
You can have multiple identifiers refer to the same physical IP address.

Likewise a 1800 number (especially one that is linked to alphabetic
characters on a telephone keypad) can operate a bit like a domain name.  You
could theoretically add different number ranges like 1900, etc for the
equivalent of "com.au", "net.au" etc.
Note the telephone number has a direct relationship to charging/billing
which the domain name does not.

Regards,
Bruce