One nice feature of SIP is the ability to have an easy-to-remember URI rather than a long phone number to contact someone with.
By default Trixbox doesn't give you an option to assign an alias, and you are stuck with receiving calls only to your extension numbers. If someone from outside your organization wants to call you, they have to call something like sip:firstname.lastname@example.org.
The good news is that we can manually add these aliases into the Asterisk configuration files.
From the Trixbox admin web interface, select Asterisk, then Config Edit. Select extensions_custom.conf, and add the following to the end of the file.
exten => ryan,1,Goto(400,1)
exten => support,1,Goto(400,1)
exten => mark,1,Goto(401,1)
exten => jason,1,Goto(402,1)
This example will forward any calls to email@example.com or firstname.lastname@example.org to extension 400, calls for email@example.com to extension 401, and calls for firstname.lastname@example.org to extension 402.