The DCME Package is used for interfacing digital circuit multiplication equipment (DCME). DCME types are for instance, defined by [b-ITU-T G.763], [b-ITU-T G.767] or [b-ITU-T G.768]. There is a signalling interface defined between DCME and a so-called "international switching centre" (ISC). [ITU-T Q.50] defines such an interface. The DCME Package scopes DCME with Q.50 interfaces (see Figure 1).

NOTE 1 – Relation to PCME [b-ITU-T G.765]: the DCME package may be applied in principle as well for PCME types with Q.50-based CME signalling and E1/PDH trunk interface types. The final decision is still for further studies, e.g., due to dependencies with the still open clause 19 of [b-ITU-T G.765] on dynamic load control.

NOTE 2 – Relation to IP-CME [b-ITU-T G.769]: the DCME package may be applied for IP-CME types with Q.50-based CME signalling and E1/PDH trunk interface types. Other trunk facilities are for further study.

The DCME Package must support DCME-ISC signalling interface functions. The required Package capabilities may be summarized by the following overview from [b-ITU-T G.763] and [ITU-T Q.50]. There are three major groups of functions:

• Transmission resource management

Facilitates the dynamic load control process within the ISC and the DCME concurrently, based on the status of the traffic loading on the DCME system.

• Seizure/release of 64 kbit/s circuits

Used in the DCME for the generation of internal assignment and disconnection messages and in the ISCs for the validation of circuit seizure selection/release based on acknowledgement from the DCME.

• Maintenance information

Facilitates information exchange between the DCME and the ISCs pertaining to the maintenance status. Maintenance status information may be exchanged between the DCME and the ISC.