and if it's important, they should call you.
I'm sorry, but I DON'T WANT A PHONE CALL! I'd much rather get an email/SMS and respond quickly, efficiently and without the extra "chatter" that happens during the course of a normal phone call.
Maybe I've finally become the anti-social, datacenter-dweller with no ties to the rest of humanity, but I've found that people are stupid and talking to them wastes time. Quick and precise email makes life so much easier. Tell me what the problem is and I'll fix it... then I'll email you back. My blackberry allows me to do this from just about anywhere (inclusive of the "fix it" portion of the transaction).
I admit... the problem with this approach is expecting stupid people to clearly express their issue via text. Most can't do it verbally, so asking them to type it out is a chore.
It is done to create frustration and a strong determination to find ways of making our lives work with this new technology so that we don't notice that we don't actually need it.
Only slightly off topic...
http://www.theonion.com/content/video/sony_releases_new_stupid_piece_of
If all else fails, lower your standards.