As others have said, "yes" It does take practice, but there are other elements of female speech besides pitch, resonance, phrasing, vocabulary, for example, that combine to create a natural speaking voice that's reliably perceived as female. One way to start, is simply by opening your mouth more and letting the words come out naturally. You can try changing your resonance by standing in front of a wall mirror and speaking to the mirror. Men speak with the words coming from the chest, as if they're speaking to the back of a large room. By speaking to a mirror, you're beginning to train your voice to speak to a closer target, and try to bring the words from the back of your throat as you speak close up. With your words coming from the back of your throat and having your mouth open wider, you can begin to raise the pitch as your speech flows from your throat. Buy the Boss TU-80 guitar tuner from
Amazon.com so you can have visual feedback as you practice. This is the tuner recommended by one of the online speech programs, Exceptional
Voice.com. It's difficult to practice blind...the visual feedback is an essential, and low cost guide.
I haven't been perceived as male over the phone in years. My target pitch is A3. I'll drop down to G3, and in daily speech, my voice fluctuates all over the spectrum from G3 on up. Room must be available for inflections, so it isn't practical to set a high pitch as a starting point. Regardless of your starting point, try to set a target that's comfortable for you, and work from there. G3 or A3 works well for most who are training their voice, and those serve as good target pitches that are in the female range of speech. Even if your pitch is low, as long as you can vary your pitch through the proper use of inflections, and your resonance is good, you can accomplish quite a bit.