using Trixbox, the + character is reserved in outbound routes so i had to use extensions_custom.conf to make the following changes…

[from-internal-intldial]
exten => _+61XXXXXXXXX,1,Goto(from-internal,0${EXTEN:-9},1)
exten => _*X.,1,Goto(from-internal,${EXTEN},1)
exten => _X.,1,Goto(from-internal,${EXTEN},1)
This allows  my saved phone entries witha + to work.

Obviously, unless you live in Australia,  you may want to change the +61 to something else.

Also, even though asterisk doesn’t appear to list + as a dialplan option, it works.

Tested in asterisk 1.2.4 and 1.2.5