How can a voice change so much over the phone?

I am doing a college project with this chick and she does have a deep voice, but she still sounds girlish when I talk to her face to face...But when I was discussing what we are gonna do on the phone she sounded like a guy... The first time she called I thought someone was pulling a prank on me..How can a voice change so much over the phone?
its like a voice recorder, they dont and cant

get the exact sound and pitch of what it really

sounds like, unless its like really high quailty, even still

it cant get the exact tone and sound...How can a voice change so much over the phone?
lol lol lol oh gosh yeah ive notice that kinda thing too ! not only over the phone , i think over mic as well as recording , the voice changes ..hehe ive no idea why thou lol but thanks for pointing that out coz when i told me friends that they dont really think that its such a big change thou i feel so !!
lol and know exactly what your talking about.my bf has a deep voice and when ever we are talking on the phone in like baby you really talk like a girl over the phone.my mom answered my phone phone and ma boyfriend said hi baby.my mom was like are you lesbian to me.i was like no.she said well a female contact in your phone called and said hi baby whats up.
haaaaaaaaaaaaaa. your right,and funny. i had to reply to this.haaaaaaaaaaaaaaaaaaaaaaaaaaa.haaaaa?also i added you to my contacts. later homeboy!