Not sure if relevant, but here goes anyway.
I've been cursed (maybe blessed, not sure), with a fairly light voice; it's unmistakeably male, most of the time, but when I answer the phone, I tend to go into some sort of Hyacinth Bucket-style thing, and can end up sounding disturbingly like my sister might, if I had one. This is important.

Anyway, when I was living at home, and unemployed, I'd quite often be the only one in the house during the day, so I'd answer the phone every time it rang. Usually it'd be a relative or friend wanting to chat, but every so often, it'd be someone from some telesales company somewhere.
Every time it was, without fail, they'd assume I was a woman- or, to be precise, a girl. Sometimes, by the way they'd talk, they'd think I was at least legal, other times they'd talk to me like I was some obviously-rebellious lass skiving off school.
Usually I'd be ever-so-polite, and courteous, and tell them my parents would be home later, and they could call back later, thankyouverymuch. Sometimes, if I was particularly annoyed, I'd tell them in my gruffest (not very, really) voice that I was, in fact, the younger of the Misters of the household.

Once in a blue moon, I'd have some fun.

This particular day, for one reason or another, I was in a foul mood. The phone rang, I answered, and immediately this guy said 'hello, darling. Are you the lady of the house?'.
I said that yes, I was.
what proceeded was about fifteen minutes of him half-telling me about his wunderproduct, and half-flirting. Badly.
I played along with it, until, just as he said 'alright, thanks for listening' or something like that, I told him my name was Dave, and that he really needed to work on his pickup lines.
(BornToBeBemused was born,feeling bemused,on, Thu 23 Feb 2012, 13:23, 4 replies)

I get this, too.
I am often addressed, by cold callers, as my wife, or my mother (or, in one case, my wife's deceased grandmother).
Sometimes, they'll apologise, sometimes they'll carry on addressing me as a woman, long after I've corrected them.
The most memorable was the nice lady at the clinic, calling to confirm the date for my vasectomy: assumed I was my wife, apologised when corrected, then kept asking "are you sure you're him?" as we went on.

Does wonders for my self esteem.
( monster munch person, man, woman... camera... TV?, Thu 23 Feb 2012, 13:31, closed)

You needn't have bothered with the vasectomy
after the castration
( Snappyuk gets BIGGER with free sample., Thu 23 Feb 2012, 16:33, closed)

Someone had to make that joke.
I'm glad it was you.
( monster munch person, man, woman... camera... TV?, Thu 23 Feb 2012, 19:16, closed)

Back when I still lived at mum and dad's house with my brother
one of my favourite things to do when one of these idiots rang was to reply to the question "Hello, can I speak to Mr. Funkenschlag?" with the response "You've got a choice of three, pick one."

Hilarity, and mumbling, would ensue.

edit: I've not been mistaken for a woman though
( Funkenschlag still likes dogs more than cats, Thu 23 Feb 2012, 13:38, closed)