Caller I.D. and liars

Why do people lie? More specifically, why do they lie and say they tried to call you? A conversation I had with my ex last night went a little something like this:

Me: I'm calling to find out where your mom is. (She had been in the CCU for over 2 weeks and now the hospital said she was no longer a patient.)

Him: Didn't April call you?

Me: No

Him: I been trying to call you.

Me: Did you get my machine and leave a message?

Him: I got some digital recording. I know what your message sounds like but all I kept getting was this weird digital recording.

Me: According to my caller id, you haven't called since your mom went in the hospital.

Him: (Quiet pause). I must be hitting a wrong digit or something.

Uh huh, sure. Why do people persist in the lie when they know they've been caught? It's enough to make me scream: LIAR!! LIAR LIAR LIAR!!!!

Okay, occasionally the caller id fails but when i have 4 phones with caller id, come on.