Glossary

For a complete list of abbreviations and glossary, see the description for ACRONYMS, ABBREVIATIONS AND GLOSSARY.

Here is a list over some common terms used in this document:

CAS

Channel Associated Signaling (legacy trunk protocols)

CSI

Call Service Information, a type of call information.

CCS

Common Channel Signaling trunks, such as DPNSS, DASS, ISDN, H.323, SIP.

DPNSS

Digital Private Network Signaling System (tie-line protocol defined by BT)

FRL

Facility Restriction Level, an 8-level (0-7) priority and protection information for route access, which can also be assigned to extensions and routes as calling party, indicating which routes they are allowed to access.

H.323

IP Standard defined by ITU-T, here as tie-line protocol.

ISDN

Integrated Services Digital Network (defined by ITU-T)

MFC

Multi Frequency Compelled (trunk signaling)

Priority Routing

A function that will route trunk calls based on a priority information

Priority Disconnect

A preemption function that will disconnect used trunk resources for a call of lower priority, and use these trunk resources for a new call, with higher priority.

TCM

Traveling Class Mark, basically the same as FRL, but when sent via a tie-line in the private network.