Lift the receiver. If you have dial tone at the NID, the trouble is with either a phone set, accessory, jack or inside wiring. Inside wiring can be repaired by Triangle Communications or by another company, as long as the work meets safety requirements.
If there is no dial tone at the NID, the trouble may be outside of the home. Call Triangle at 1-800-332-1201 to report no dial tone at the NID 24 hours a day, seven days a week.
Make sure to place the modular plug back in the test jack.