In Channel

Common Channel

Trunks are held up during signalling.

Trunks aren't required for Signalling

Signal repertoire is limited.

Extensive signal repertoire is possible.

Interference between voice and Control signals may occur.

No interference as the two Channels are physically separate.

Separate signalling

Only one set of signalling

Equipment is needed for each trunk and thus expensive.

equipments is essential for a whole group of trunk Circuits and hence CCS is economical

Voice channel being the control channel, there is a possibility of potential misuse by the customers.

Control Channel is in general in accessible to users.

Signalling is comparatively slow.

Signalling is significantly fast.

It is difficult to change or add signals.

There is flexibility to change or add signals.

It is difficult to handle signalling during speech period.

Signals during speech. There is freedom to handle

Reliability of signalling path is not Critical.

Reliability of the signalling Path is critical.

Speech circuit reliability is assured.

There is no automatic test of speech circuit.

Common channel signalling is better than In-channel signalling.