I used to be in the same spot. I went twelve years in call center hell. And my friends still call me the girl with the 1-900 voice.
I'm not going to say it goes away completely, but it does get better.
My tactics were to go as clinical and professional as I could, but not monotone. There's a place in the middle where you can be friendly sounding and professional. It just takes practice to get to.
A lot of commercials use that type of speaking, if you need examples. Uhm.. trying to think of one. Disclaimer voices, talking about medicines other than Viagra usually have that style.
I also worked to deepen my tone. I got to where I could get to a certain level that both men and women responded to well, but not flirty. Occasionally I would allow a little more friendliness to pop in, if the customer on the line deserved it. :)
You'll still get the insensitive clods who think it's their prerogative to hit on any female sounding voice. But the casuals will behave more.
Every place I worked had their own special pervies. I wish I had a place like RHU back then where I could have vented about ours!