Communication Technology: CIC identification code

 

CIC: Circuit identification code

CIC is the circuit identification code (circuit identification code). The lowest five bits of CIC indicate the actual time slot number allocated to the phone, and the other seven bits represent the PCM System Identification Code of the origin and destination.

In ISUP or Tup messages, the length of CIC encoding is fixed to 12 bits. Therefore, when both exchange bureaus adopt the single signaling point encoding, A single bureau can only have a maximum of 212 = 4096 relay circuits.

In a bssap message, the length of the CIC code is fixed to 16 bits. Therefore, an A port can have up to 216 = 65536 relay circuits. Between MSC (msc server + MGW) and BSC, the CIC code of the same a-interface relay circuit (E1 time slot) must be completely consistent in order to be connected successfully, otherwise, exceptions such as phone connection failure and Crosstalk may occur.

In the two-way relay group, in order to prevent the two exchange bureaus occupying the same relay circuit at the same time lead to the phenomenon of "same grab", the ITU-T suggests that the two exchange bureaus each control half of the relay circuit, the Exchange Board with a large signaling point code controls the circuit where CIC is an even number, and the Exchange Board with a small signaling point code controls the circuit where CIC is an odd number.

In accordance with this principle, the exchange bureaus take advantage of the relay circuit of the main control of this Council. Only when the main control circuit is busy Can this Council attempt to occupy the relay circuit of this non-main control; if the two exchange bureaus compete with each other at this time, the exchange bureaus that do not control the relay circuit will voluntarily give up occupying the relay circuit (Instead, occupying the next relay circuit ).

CIC: Call instance code

The meaning of bicc cic is different from that of ISUP:

CIC in ISUP is the circuit identification code (circuit identification code) used to identify a physical circuit, identify the signaling relationship between the ISUP entities and all the signaling messages related to this signaling relationship.

The CIC in BICC is the call instance code that does not identify the physical circuit, but only identifies the signaling relationship between the equivalent ISUP entity and all the signaling messages related to this signaling relationship.

The CIC in ISUP is 12 bits,

The CIC in BICC is 32 bits (4 bytes), which breaks through the limit of 4096 pieces of CIC between nodes.