Dual Transfer Mode (DTM) makes synchronous convey of Circuit switched (CS) voice and Packet switched (PS) information over the similar radio channel simpler. It is dependent on the GSM standard. One normal class carried out by cell phone vendors is the DTM Multislot Class 11. In 2010, devices with DTM multislot class 32 like Nokia N900 were accessible. A synchronous voice and information call indicates that an information call might begin an ongoing voice call or a voice call may begin a continuous information call.