If you believe that text messaging and the infrastructure needed to support the likes of Apple's ( AAPL Quote ) iPhone will continue to grow, the stock of a small telecom equipment maker called Tekelec ( TKLC Quote ) presents a good buying opportunity, according to Jim Cramer. "Tekelec rocks," Cramer said during his "Mad Money" broadcast on CNBC Thursday evening. The company, based in Morrisville, N.C., near the Raleigh Durham Research Triangle, makes the equipment necessary to transmit text messages and, perhaps even more lucratively, allow users to keep their phone numbers when switching carriers, a technology that's called local number portability. Tekelec holds a 35% share of the local number portability market.