I would like to know the difference between channel associated signalling and common channel signalling.

I get very confused when I try to differentiate them.

I will be really glad if anybody can get me out of this.


Thanks in advance

Channel associated signalling means there is a one-to-one relationship between the traffic channel and the signalling channel. There is a signalling channel for every traffic channel.

Common channel signalling means that all the traffic channels use a single shared (common) signalling channel - a one-to-many relationship.

can u detail me in terms of voice and data channels?

If it is using CCS, multi-octet messages are sent on the signalling channel (out of band to the payload) that include identification of the channel being signalled. The separation of the signalling, and the use of a common channel allows the payload to have access to the full 64Kbs bandwidth. This is used with SS7, for example.

With CAS, each channel is associated with 4 bits (2Kbs) of signalling. Because the signalling is embedded (inband) with the payload, the payload speed is reduced to 56Kbs. You'll also see this referred to as robbed bit signalling, since you're stealing bits from the payload.