As the adoption of smartphones continues to surge, and with three-quarters of all cellphone owners texting on a regular basis, the mobile gadgets have become the hotbed for digital scams and spam. Many of the frauds are originating via text message. “The same threats that exist on a PC exist for cellphone users,’’ said Greg Post, T-Mobile’s vice president and general manager for the Mountain West region. The latest scam catching fire in the U.S. involves a purported request for iPhone 5 testers. Potential victims receive a text telling them that the first 1,000 users to enter a code supplied in the message at a specific website will get to “test and keep a new iPhone 5.’’