No it's not Christine's cell number. Your own phone number does not show up on the screen of your own cell phone when trying to call someone else from your cell phone. It is THE NUMBER OF HER BOYFRIEND, CLAY, from said movie. During her second main visit from the Lamia, she tries to call him from her phne. This is the number it shows her dial, under the name Clay. It is quite strange however for Sam Raimi to use a number that could be real, rather than the typical movie phone number style 555-XXXX.