Match one or more digits

Asterisk Asterisk Dialplan
1

This may be a dumb question, but how do I match a sequence that has one or more digits, or at least, begins with a digit and can contain an arbitrary number of characters? I can use:

_X!

but that won’t work in transfer context, as it will always match immediately on first digit.

2

see Blind/Assisted Transfer

3

In other words, what I want is not possible with a single pattern. I must use two extens (_X and _X.) and duplicate the functionality. Seems like a design flaw to me.