Blacklist/whitelists

[Tim Newsom]

On a related note to all of this sms talk... Can you send an sms with 
delivery receipt to a range of addresses and get back notification for 
all phone numbers which actually exist? (Obviously it will be one at a 
time, not boradcast)

Or does it just return success once it changed network providers and it 
doesn't matter?

Basically, could you use this to find out the network that owns a bunch 
of numbers or to find out which network a number belonged to in some 
way?
--Tim