Ah NickyG, the very thing happened to me.
I received a complaint phone call from one of our clients at work, and by the end of the call, I had her giggling, and she actually remarked how pleasant (read - sexy) my phone manner was with a flirtatious giggle - i told her i knew. A lot of masculinity can be portraid over the phone... however, I knew from one of my onsite staff that she wasn't my type, so nothing became of it...
you are right though, for every time that has happened to me, it's a running joke with my colleague when we end a phone call to remark 'she wants me'
good show