the simplest (NOTE THE DOTS!!!):
match: +x. (with dot, dot means any repeat of x ([0-n] times), x is any character) - this will match any phone mumber starting with +.
These patterns are part of VoIP dialplan standard, not our invention.
BTW: x. will match any phone number. this could be useful for e.g. always adding 9 before the number.
You could be more precise, e.g.
match: +32x. - something that starts with +32
match: +32xxxxxxxxxx - something that starts with +32 followed by 10 digits
But the syntax allows much more complex matches.
To see what is the outcome of the processing, click the contacts number (as ususal) and the call confirmation action sheet will show the final number (processed).
I made the topic sticky. If you have questions / examples to share about the Dial Plan we can continue this topic here.
Based/inspired by on industry practice e.g.:http://en.wikipedia.org/wiki/Telephone_numbering_plan