asterisk users - Apr 2006 - do extensions must be numbers in Asterisk@Home?

Hello to all
In Asterisk, SIP clients can be registered with numbers (2001, 2002, 
...) or with names (manuel, maria,...).
But Asterisk@Home only allows SIP registers to be done with numbers...
Is there any way of register SIP users with names and then give them a 
numeric alias?

Thanks
Joao