Basic Rules
A) Never ask how she is or what she's doing. It just gives her an excuse not to talk to you - don't give her the option.
B) When she answers the phone, open up with high energy (slightly higher than hers). Bring her energy and interest level back (psychologically) to when she first met you.
C) Open with a routine:
Example:
You - "Do you have a twin I should know about?"
Her - "No....why?
You - "So I just got out of the gym, and and I met your someone that looks exactly like you. I was about to call NASA to put you on the moon. One of you, I could deal with, but 2 would be way too many...
"D)Have stories - there's nothing worse than an awkward silence. However, when used correctly, can be an interest gauge test. For example, if you quiet down and she reinitiates the conversation; you know she wants to talk to you.
E) Always be the one to end the phone call.
F) If you want to show that you're pre-selected, tell her you've got another call and put her on hold (not for too long, but make her wait a little bit - it will work miracles.
G) If you get her voicemail - Leave a message. Have high energy and leave some ambiguity. If you entered your number in her cell - no need for introductions - just say the line. If you only got her number and she doesn't have yours, just say "Hey, it's [NAME]" and continue.
Example:
"Hey you, so I just met your twin."
"Have you ever been to Paris?!"
"I didn't know you knew my friend Kelly."
"You will never believe what just happened!"
Short & Sweet.