Telecommunications Industry Association tr41 1/05-08-009 Document Cover Sheet



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Telecommunications Industry Association TR41.1.1/05-08-009

Document Cover Sheet

Project Number

SP-3-0191: Standard for a Packet-based VoIP Terminal Adapter Analog Telephone Port

Document Title

Questions concerning TR41.1.1/05-08-003

Source

Infineon Technologies

Contact

Michael Pirker

Infineon Technologies

1730 North First Street

San Jose, CA 95112

U.S.A.


Phone: (408) 501-6713

Fax: (408) 501-2486

Email: michael.pirker@infineon.com


Distribution

TR-41.1.1

Intended Purpose of Document
(Select one)


x

For Incorporation Into TIA Publication




For Information




Other (describe) -

The document to which this cover statement is attached is submitted to a Formulating Group or sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of which provisions are hereby incorporated by reference.

Abstract

We have some concerns about some of the proposals to change the draft of TIA-1063 in TR41.1.1/05-08-003, “Modification to some clauses and subclauses of TR41.1.1 draft document”.



Item 3 / TR41.1.1/05-08-003: Disconnect Signal

  • States: “Section 5.1.11.5 describes a disconnect signal that is sent by the ATA. For clarity, it needs to be defined what it is.”

  • Proposes: “Add – Analog Telephone adapter disconnect signal appears as no DC voltage (no loop current) between tip and ring for a period of at least 600 ms.”

However, when looking at Section 5.1.11.5, we find:

        1. It is desirable that the analog telephone port transmits a disconnect signal as described in 5.1.11.2 toward the analog telephony equipment within 2 minutes after detection of a permanent or partial-dial time-out at the analog telephone port.

And when following up the reference at Section 5.1.11.2, we find:

        1. The analog telephone port shall remove dial tone within 500 ms after receiving the start of the first DTMF digit.

So actually, Section 5.1.11.2 does not describe a disconnect signal at all.

Probably what was intended is Section 5.1.14.2, which defines a disconnect signal.



        1. If flash signals generated by the analog telephony equipment are not used by the terminal adapter to initiate internal calling features, the terminal adapter shall interpret on-hook intervals of 1500 ms or greater as valid disconnect signals.

Our proposal:

  • Correct the reference in Section 5.1.11.5 from “5.1.11.2” to “5.1.14.2”;

  • Do not accept the change from 1500 ms to 600 ms.

Item 4 / TR41.1.1/05-08-003: On-hook Interval

  • States: “Section 5.1.14.1 has the ambiguity of on-hook time interval between 150 ms to 300 ms. This period should either be included on the ignore side (item 1) OR itemize the period as reserved for future use.”

  • Proposes: “In Section 5.1.14.1, add another subheading between 1 and 2 as ‘Reserved on-hook intervals of 150 ms to 300 ms for future use.’”

However, when looking at Section 5.1.14.1, we find:

5.1.14.1 If flash signals generated by the analog telephony equipment are used by the terminal adapter to initiate internal calling features, the terminal adapter shall:

(1) Ignore on-hook intervals of 150 ms or less.

(2) Interpret on-hook intervals of 300 ms to 1.1 second as valid flash signals.

(3) Interpret on-hook intervals of 1.5 seconds or greater as valid disconnect signals.

The proposal of -003 is to introduce a 4th state for the on-hook interval between 150 ms and 300 ms, for future use.



We have two objections to this proposal:

  • Isn’t it important to include some margin for implementation? Just as there is between the 1.1- and the 1.5-second gap?

  • Could there be unintended implications for higher-layer applications from changing the protocol in this way?

Our proposal: Do not change the interpretation of the on-hook interval.



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