Q. Compare in-channel signalling with common channel signalling?
Network wide signalling also involves end to end signalling between originating exchange and the terminating exchange. Such a form of signalling is known as line signalling. CCS doesn't use the speech or the data path for signalling. It employs a separate common channel for passing control signals for a group of trunks or information.
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In Channel
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Common Channel
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Trunks are held up during signalling.
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Trunks aren't required for Signalling
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Signal repertoire is limited.
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Extensive signal repertoire is possible.
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Interference between voice and Control signals may occur.
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No interference as the two Channels are physically separate.
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Separate signalling
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Only one set of signalling
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Equipment is needed for each trunk and thus expensive.
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equipments is essential for a whole group of trunk Circuits and hence CCS is economical
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Voice channel being the control channel, there is a possibility of potential misuse by the customers.
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Control Channel is in general in accessible to users.
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Signalling is comparatively slow.
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Signalling is significantly fast.
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It is difficult to change or add signals.
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There is flexibility to change or add signals.
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It is difficult to handle signalling during speech period.
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Signals during speech. There is freedom to handle
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Reliability of signalling path is not Critical.
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Reliability of the signalling Path is critical.
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Speech circuit reliability is assured.
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There is no automatic test of speech circuit.
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Common channel signalling is better than In-channel signalling.
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