Each time SLOT on a TDMA frame is called a physical channel. Therefore, there are 8 physical channels per carrier frequency in GSM.

Physical channels can be used to transmit speech, data or signaling information. A physical channel MAY carry different messages, depending on the information which is to be sent. These messages are called logical channels. For EXAMPLE, on one of the physical channels used for traffic, the traffic itself is TRANSMITTED using a Traffic Channel (TCH) message, while a handover instruction is transmitted using a Fast Associated CONTROL Channel (SACCH) message.

Each time slot on a TDMA frame is called a physical channel. Therefore, there are 8 physical channels per carrier frequency in GSM.

Physical channels can be used to transmit speech, data or signaling information. A physical channel may carry different messages, depending on the information which is to be sent. These messages are called logical channels. For example, on one of the physical channels used for traffic, the traffic itself is transmitted using a Traffic Channel (TCH) message, while a handover instruction is transmitted using a Fast Associated Control Channel (SACCH) message.