In modern communications, trunking is a concept by which a communications system can provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually.


E1 - 2048Kb/sec - 32 channels (64Kb/sec) - Common Channel Signalling - Out-band
Channel 0 E1 sync/error checking
Channel 1-31 DS0 channels for voice

T1 - 1544Kb/sec - 24 channels (64Kb/sec) - Common Channel Signalling - In-band
Channel 0-23 DS0 channels for voice (robbed bit from each channel for signalling/error checking)

ISDN PRI over E1 - 2048Kb/sec - 30 channels (64Kb/sec) - Channel Associated Signalling - Out-band
Channel 0 E1 sync/error checking
Channel 1-15 DS0 channels for voice
Channel 16 ISDN D signalling
Channel 17-30 DS0 channels for voice

ISDN PRI over T1 - 1544Kb/sec - 23 channels (64Kb/sec) - Channel Associated Calling - Out-band
Channel 1-23 DS0 channels for voice
Channel 24 ISDN D signalling