Frame:

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Pulses streaming in a T1 circuit would be meaningless if there was no way to organize them in a meaningful structure. In T1, bits are organized into 192 bit frames with an associated single frame bit for a total of 193 bits. The frame bit pattern has unique characteristics that allow the receiving end to recognize it and to synchronize to it. D3/D4 framing patterns have the ability to identify a super frame of 12 sub-frames. Extended Super Fame (ESF) has the ability to identify a super frame of 24 sub-frames and include a data link channel and Cyclic Redundancy Checksum (CRC) check bits.