Teasing on the phone comes with a lot of extra work, mainly because you're losing the physical element of speaking face to face, reading their facial cues, and knowing what turns them on or not. Your best when flirting through text or call is by using humor. Keep your text messages light and funny, making jokes or funnily retelling your stories.  However, it is vital to note that not everything you say needs to be funny. All other guys might be trying too hard to make everything they say or text funny, so it's up to you to be the difference. Know when to be serious and make her laugh; with this, she might never lose interest.