Telephones

When you provide phone numbers, please provide phone numbers that actually work.
Many a time work cannot start on customer PCs because we cannot get in touch with them, then they have the audacity to phone back saying they've heard nothing from us when it turns out the number was either wrong in the first place or was disconnected six weeks ago.

It's weird how people don't know their own mobile number. They'd have had to give it out to friends and family enough times, you'd have thought, or rang their own number to find out where they'd left it on occasion. This concept never happens with landline phones and people rarely forget their house phone number which, ironically, they'd have had to give out just as many times as their mobile.