Subject: Cisco SG16: Signals Operation

From: Chip Sharp <[email-masked]>
Date: Tue, 25 Jan 2000 19:58:49 -0500

Section:        7.1.10, fourth paragraph, first bullet.
Category:       Technical, Open Issue
Issue:          The draft text defines on/off signals "the signal lasts until it is
turned off", however this definition is not clear. Specifically, it is not
clear if an on/off signal is turned off by not being included in a
subsequent SignalsDescriptor or if it is turned off by some explicit
action. In the latter case, syntax is missing leading one to believe that
the former definition is intended. The former definition on the other hand
is somewhat problematic and overlaps the definition of time-out signals
with an indefinite duration. Consider for instance a "visual message
waiting indicator" defined as an on/off signal. Unless the signal is
included in all subsequent SignalsDescritpors, the indicator will be turned
off. The on/off signal type would be more useful (and not a duplicate of
timeout) if this was not the case.
Also, it should be noted, that the more general topic of signal types and
the details of their operation has been the subject of much debate on the
IETF Megaco mailing list since the white contribution was developed, and
that at time of writing, no resolution had been found.

Proposal:       It is recommended that the definition of on/off is clarified in
accordance with the above and the missing syntax added.

v13 Status:     OPEN. No substantial change has been made.

Section:        7.1.10, fourth paragraph, second bullet
Category:       Technical
Issue:          The draft text defines timeout signals as "the signal lasts until
it is turned off or a specific period of time elapses", however there is no
mechanism specified for informing the MGC when that specific period of time
has elapsed and thus the signal has ended. The MGC may therefore be unable
to determine if a given signal is playing in an MG or not. An example where
this is needed is outpulsing with MF Feature Group D trunks where multiple
digit strings (address and caller id) need to be outpulsed. MGC needs to
know when outpulsing of the first string of digits has occurred before
requesting out-pulsing of the next string.). Another example is a signal
activated through an external event such as user input (by use of an
embedded signals descriptor).

Proposal:       It is strongly recommended that a mechanism for notifying the MGC
upon timeout signal completion is added, e.g. in the form of an event
("operation complete"). Furthermore, it should be considered to add another
event that would allow the MGC to be informed if generation of the signal
fails for some reason (e.g. "operation failure"). It should be noted, that
this may happen in the middle of the signals defined duration.

v13 Status:     OPEN. No substantial change has been made.

Section:                12.1.4
Category:       Technical, Open Issue
Issue:          The draft text mentions SignalType CN (Continue), however this
SignalType is not defined in Section 7.1.10 on Signals Descriptor.
Also, it should be noted, that the more general topic of signal types and
the details of their operation has been the subject of much debate on the
IETF Megaco mailing list since the white contribution was developed, and
that at time of writing, no resolution had been found.
Proposal:       It is proposed that SignalType CN is removed from the text.

v13 Status:     OPEN. No text changed.

Section:        12.1.4
Category:       Technical, Open Issue
Issue:          The draft text specifies that "Signals that would be played with
SignalType BR should have a default duration"
Again, it should be noted, that the more general topic of signal types and
the details of their operation has been the subject of much debate on the
IETF Megaco mailing list since the white contribution was developed, and
that at time of writing, no resolution had been found.
Proposal:       It is proposed that similar text is added as for signals of
SignalType TO.

v13 Status:     OPEN. No text changed.

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Chip Sharp                 Consulting Engineering
Cisco Systems              Telco Bio-region
Reality - Love it or Leave it.
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