ITU-T H.248.26 PDF

The Analogue Line Supervision package defined in Annex E of [ITU-T H.248.1] supports basic telephony services, using on-hook and off-hook events, and a ringing signal. Some telephony services delivered over analogue line terminations have additional supervisory signalling requirements that are not met by the Analogue Line Supervision package. The packages defined in this Recommendation are intended to meet the needs of the following supervisory signalling functions:

– Line-side answer supervision: This function provides a positive notification to a calling line that the called line has answered. This notification may be used by customer premises equipment, for example, to begin timing the call for local billing or charging purposes.

– Network disconnect: Many switching systems provide this signal following the termination of an active call if a party remains off-hook for some period of time following the other party going on-hook. The network disconnect notification may be used by customer premises equipment to release resources associated with the call.

– Metering pulses: Metering services provide subscribers with real-time information about charging of calls in progress. These services make use of customer premises equipment that shows a count of "units" consumed by chargeable calls, where each unit has a fixed monetary value. To increment the counter in the metering equipment, the switching system sends certain kinds of pulses over the line, either during the call or immediately following termination of the call. These pulses typically consist of short bursts of 12-kHz or 16-kHz tones, although other types of metering pulse such as brief periods of polarity reversal or 50-Hz tones are also seen.

To meet these needs, two supplemental packages are introduced:

– The Extended Analogue Line Supervision package is defined as an extension of the Basic Analogue Line Supervision package, and includes two new signals: Line-Side Answer Supervision and Network Disconnect. This package provides support for all the Loop-Start supervisory signalling requirements identified by [b-Telcordia GR-506-CORE].

– The Automatic Metering package provides a means to apply metering pulses on an analogue line termination. The package includes:

• signals requesting the automatic application of pulses at fixed intervals as well as the application of pulse bursts;
• statistics that may be used to track the actual number of pulses applied;
• and an event that may be used to trigger periodic reporting of the count of pulses applied.

This Recommendation introduces a phased metering signal suitable for use with complex metering scenarios. It also introduces a new metering detection package that can be used to instruct the MG to detect and report metering pulses generated by a network peer.

The support of these packages is optional.