It’s easy to change your Caller ID (assuming your phone provider doesn’t filter it) in Asterisk using something like Set(CALLERID(name)=blah). This is often used to choose which number to use for an outgoing call if you have multiple on a single SIP or ISDN trunk.

But did you know it’s just as easy to change the Callee ID on an outgoing call, i.e. change what your phone displays during the call? This can be very useful to display on the phone which one of several possible outgoing lines (multiple SIP providers, ISDN, …) was used or at which point in an IVR menu you are at the moment. To do this, use Set(CONNECTEDLINE(name)=blah). Before getting started, set sendrpid = pai in your sip.conf.

To make things easier, I created two macros in my dialplan:

[macro-connectedline-name-number]
exten => s,1,Set(CONNECTEDLINE(name,i)=${ARG1})
exten => s,n,Set(CONNECTEDLINE(number,i)=${ARG2})
exten => s,n,Set(CONNECTEDLINE(pres)=allowed)

[macro-connectedline-name]
exten => s,1,Macro(connectedline-name-number,${ARG1}, ${MACRO_EXTEN})

Now I can do things like

[internal-test]
exten => 101,1,Answer()
exten => 101,n,Macro(connectedline-name,Hello World)
exten => 101,n,Playback(hello-world)
exten => 101,n,Hangup()

in my dialplan (IVR example).

Or how about

[outgoing]
exten => 100,1,Macro(connectedline-name,Mailbox)
exten => 100,n,VoiceMailMain(${CALLERID(num)},s)
exten => _XXX.,n,Macro(connectedline-name,VoIP 1)
exten => _XXX.,n,Dial(SIP/${EXTEN}@voipprovider)

(outgoing line example).

The Asterisk Wiki also has an entire page on Manipulating Party ID Information.