:-) Nick and Schanke both have cell phones right from the start of the series (the phones get visibly smaller each season).

If I remember correctly, Schanke has to pull out the antenna of his cell phone before he uses it to call Myra in "Dying to Know You" (he uses a pay phone to call Myra in "For I Have Sinned"). And in some episode that's slipping my mind right now, Schanke says that he "can't believe" that Nick is letting Schanke use Nick's "car phone" to make long-distance calls because they're so expensive that way. :-)