asterisk users - Sep 2008 - identify/find a channel to pick it up

hello,

i want to build a pickup extension in a multiuser system, which means
there are several different numbers which same extensions and so on. the
phonenumbers are identified only with their ID in the database like
+123- where after the - is the extension.

the normal pickup function works with extension at context but the problem
i have is that i dont know the extension. so i could read out every
possible extension from the db and build a pickupstring, but i think
this would kill the system (if there are more than 200 extension on a
number). this is for a global pickup function to pickup the next ringing
channel for that number.

the other way is that i could find the right channel, so i want to
search for every channel which have the state ringing and the extension
+123-... or is there something like a wildcard i can use for pickup like
+123*


sorry for my bad english, i hope its understandable what i mean.

best regards

steve smith