Network-to-Customer Installation Interfaces Analog Voicegrade Switched Access Lines with Distinctive Ringing Features

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1 This version (R3) of the draft proposed revision of the interface standard for Switched Access Lines with Distinctive Alerting Features contains the text and tables from T1E1.1/0-013R2 with the following changes: - Several editorial changes were made as a result of comments associated with T1 LB 860. See T1E1.1/0-051R1 and T1E1.1/ NOTICE This is a draft document and thus, is dynamic in nature. It does not reflect a consensus of Committee T1- Telecommunications and it may be changed or modified. Neither ATIS nor Committee T1 makes any representation or warranty, express of implied, with respect to the sufficiency, accuracy or utility of the information or opinion contained or reflected in the material utilized. ATIS and Committee T1 further expressly advise that any use of or reliance upon the material in question is at your risk and neither ATIS nor Committee T1 shall be liable for any damage or injury, of whatever nature, incurred by any person arising out of any utilization of the material. It is possible that this material will at some future date be included in a copyrighted work by ATIS. ANSI T Secretariat Alliance for Telecommunications Industry Solutions Approved American National Standards Institute, Inc. American National Standard for Telecommunications Network-to-Customer Installation Interfaces Analog Voicegrade Switched Access Lines with Distinctive Features Abstract This standard provides the signaling requirements associated with Distinctive features on analog switched access lines when this capability is provided by the network. This standard is intended to be used in conjunction with American National Standard for Telecommunications Network-to-Customer Installation Interfaces Analog Voicegrade Switched Access Lines Using Loop-start and Ground-start Signaling, T

2 Contents Page Foreword...ii 1 Scope Normative references Definitions, abbreviations, acrony, and symbols General information Distinctive alerting by ringing signals Distinctive alerting by call waiting tone patterns Open switch intervals... 6 Tables 1 Distinctive ringing pattern objectives at the NI Annex A Distinctive ringing patterns produced by the network... 7

3 Foreword (This foreword is not part of American National Standard T ) This American National Standard is one of a series of carrier-to-customer installation interface standards developed by Technical Subcommittee T1E1 of Accredited Standards Committee T1, Telecommunications. Committee T1 standards serve the public interest through promoting understanding between carriers, end-users, and manufacturers. This standard provides the signaling requirements associated with distinctive ringing features on analog-switched access lines when this capability is provided by the network. This standard is intended to be used in conjunction with American National Standard for Telecommunications Network-to-Customer Installation Interfaces Analog Voicegrade Switched Access Lines Using Loop-start and Ground-start Signaling, T When the network provides this feature, it conveys information to the Customer Installation (CI) receiving the call about the called number, the calling number, or the status of an automatic call request. This standard will be useful to those engaged in the provisioning or operation of telecommunication equipment or services that use the distinctive ringing features on analog-switched access lines. It establishes the requirements at the network-to-customer installation interface, designated the Network Interface (NI). Compliance should provide compatibility in most installations. Existing distinctive ringing patterns produced by the network are described in Annex A. ANSI guidelines specify two categories of requirements: mandatory and recommended. The mandatory requirements are designated by the word "shall" and recommendations by the word "should". Where both a mandatory and a recommended level are specified for the same criterion, the recommended level represents a goal currently identifiable as having distinct compatibility or performance advantages. There is one annex in this standard. Annex A is informative and is not considered part of this standard. Suggestions for the improvement of this standard are welcome. They should be sent to the Alliance for Telecommunications Industry Solutions, T1 Secretariat, 1 G Street, NW, Suite 500, Washington, DC 05. This standard was processed and approved for submittal to ANSI by Accredited Standards Committee T1 on Telecommunications. Committee approval of the standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, Accredited Standards Committee T1 had the following members: Arthur K. Reilly, Chair Gerald H. Peterson, Vice-Chair O.J. Gussella, Jr., Secretary Organization Represented EXCHANGE CARRIERS Name of Representative INTEREXCHANGE CARRIERS MANUFACTURERS GENERAL INTEREST

4 At the time it approved this standard, Technical Subcommittee T1E1 had the following members: Organization Represented Name of Representative

5 Working Group T1E1.1, which is responsible for the development of this standard, had the following participants: Trone Bishop, Chairman and editor Richard Bobilin Curtis Brownmiller William Buckley John Chen Philip Dillon Frinel Fainaru Ralph Jensen Gunter Neumeier Reagan Rice Gary Tennyson Bernard Worne Irvin Youngberg

6 AMERICAN NATIONAL STANDARD - DRAFT T Scope This standard defines the interface between network analog-switched access lines and customer installations for distinctive ringing features. This standard is a companion standard to American National Standard for Telecommunications Networkto-Customer Installation Interfaces Analog Voicegrade Switched Access Lines Using Loop-start and Ground-start Signaling, T It assumes that those characteristics of the line and customer installation that are not uniquely associated with distinctive ringing features are in compliance with T1.401 and with Part 68 of the FCC Rules and Regulations, and does not restate those requirements herein. 2 Normative references The following standards and publications contain provisions that, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. T , American National Standard for Telecommunications Network-to-Customer Installation Interfaces Analog Voicegrade Switched Access Lines Using Loop-start and Ground-start Signaling, T Code of Federal Regulations, Title 47, FCC Rules and Regulations, Part 68, Revised 1998, Connection of terminal equipment to the telephone network. Washington, DC: Federal Communications Commission, Definitions, abbreviations, acrony, and symbols 3.1 Definitions alerting signal: A signal used by the network to indicate an incoming call call waiting: A supplemental feature that uses a network-generated tone pattern to alert a busy line that the network is prepared to connect another call customer installation (CI): All telecommunication equipment and wiring on the customer side of the network demarcation point directory number: The telephone number that is dialed to reach a particular CI distinctive alerting: Special ringing or call-waiting tone patterns sent by the network to convey information to a CI about the called number, the calling number, or the status of an automatic call request distinctive call-waiting tone: A call-waiting tone pattern other than the usual nominal 0.3 s on distinctive ringing: A ringing pattern other than the usual nominal 2 s on, 4 s off ground-start signaling: A type of analog voicegrade-switched access line signaling that requires the CI to provide a ground on the ring conductor at the NI to initiate service requests loop-start signaling: A type of analog voicegrade-switched access line signaling that requires the CI to provide a low-resistance tip-to-ring dc path at the NI to initiate service requests multiple directory number service: A supplemental feature that provides the called CI with distinctive alerting for each number associated with the NI. 1 T1 standards are available from the Alliance for Telecommunications Solutions, 1 G Street, NW, Suite 500, Washington, DC, Available from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC

7 network: A combination of transmission and switching facilities used to establish communication paths network interface (NI) demarcation point: The point of connection between the network facilities and the CI open switch interval (OSI): A characteristic of many common control local switching syste that appears to the CI at the NI as a network-generated open-loop condition (no dc voltage between tip and ring) with a duration of less than off-hook state: A state in which the CI presents a low-resistance tip-to-ring dc path at the NI pattern: A sequence of ringing bursts separated by silent intervals with a defined repeating cadence ringing signal: A network ac signal applied to a terminating NI in the idle state to alert the terminating CI of an incoming call ringing cycle: A nominal 6-second sequence of ringing signals and silent intervals silent inteval: Any portion of a ringing cycle during which the ringing signal is not being applied supplemental feature (service): An additional feature associated with a loop-start or ground-start line that provides a function beyond those normally used by the network and the CI to establish calls using the public-switched network switched access line: A communication path between a network switching system and a CI voicegrade: A term used to qualify a channel, a facility, or service that is suitable for speech, data, or facsimile signals; generally with a frequency range of about 300 to 3000 Hz. 3.2 Abbreviations, acrony, and symbols ac ANSI CI CW dc FCC Hz NI OSI s alternating current American National Standards Institute Customer Installation call waiting direct current Federal Communications Commission hertz millisecond Network Interface open switch interval seconds 4 General information Alerting signals are applied to the NI by the network to inform the CI of an incoming call. The alerting signals applied by the network to CIs that do not subscribe to any supplemental features are specified in T Distinctive alerting features permit a CI to classify incoming calls based on the called directory number (see 5.6) or based on the calling directory number (see 5.7). Distinctive alerting features are also used to permit the CI to distinguish between normal incoming calls and calls that are the result of CI-activated network features such as automatic recall. Currently, two types of distinctive alerting signals are applied by the network to an NI: distinctive ringing signals; distinctive call-waiting patterns.

8 The network produces distinguishable distinctive alerting signals by producing ringing signals or call waiting tone signals with different cadences. Distinctive ringing signals are applied only when the CI is on-hook (see T1.401). Distinctive call-waiting patterns are applied only when the CI and the network are in the communication state (see T ). At the option of the end-user, the network can provide only the distinctive ringing feature to a CI or can provide the distinctive ringing feature in conjunction with the distinctive call- waiting tone feature. At the option of the end-user, the network can provide a non-distinctive call-waiting feature (only one call-waiting tone pattern) when the distinctive ringing feature is not provided. The availability and characteristics of services that use distinctive alerting features depend on the network equipment serving the NI and may vary from area to area. 5 Distinctive alerting by ringing signals 5.1 General description Several supplemental services provided by the network use distinctive alerting by ringing signals. Some of these services are described in 5.4 through 5.8. The distinctive ringing cadences used for these supplemental services depend on the network equipment serving the NI and may vary from area to area. Annex A describes the ringing cadences currently produced by the network. 5.2 CI alerting state requirements The CI shall meet the customer installation alerting state characteristics requirements in T Network alerting state requirements The network shall meet the network alerting state characteristics requirements in T Network objectives for distinctive ringing patterns The cadences, the ringing and silent intervals at the NI for distinctive ringing patterns, should meet the minimum and maximum interval durations specified in table 1. In addition, the ringing cycle should be 6s ± 600. Adherence to these limits will further enhance the ability of CI equipment to detect the distinctive ringing patterns and will help to ensure compatibility of distinctive ringing supplementary services with other supplementary services such as the calling number delivery and calling name delivery features defined in T The minimum and maximum values of the interval durations produced by the source of the distinctive ringing pattern should be 50 greater and 50 less than the corresponding values in table 1, to account for distortion of the interval durations by loop- transmission equipment. 5.5 Requirements for future distinctive ringing patterns In the future, additional distinctive ringing patterns may be required. New distinctive ringing patterns shall meet the following requirements. All ringing patterns shall have a ringing cycle of 6 s ± 600 ; All ringing intervals and silent intervals in a distinctive ringing pattern produced by the network equipment that initially generates the ringing pattern shall be greater than 175 (nominal ). This will help to ensure a minimum duration ringing or silent interval at the NI of 125. In each ringing cycle produced by the network equipment, there shall be one silent interval of at least This will help to ensure compatibility with other supplemental features, such as calling number delivery and calling name delivery, by providing a minimum silent interval at the NI of at least 3550 (nominal 4 s). 5.6 Multiple directory number service When multiple directory number service is provided on a switched access line, two, three, or four directory numbers are assigned to the access line. The maximum number of directory numbers that may be assigned to one switched access line may vary from area to area and is determined by the service provider. The ringing signal pattern that appears at the NI of the CI terminating the call is determined by the called directory number. patterns 1 through 4 in table 1 should be used for this service.

9 5.7 pattern determined by calling CI directory number There are several supplemental services provided by the network in which the ringing pattern applied to the access line of the terminating CI is determined by the calling directory number. One service indicates by the ringing pattern whether the incoming call is from a directory number in a predetermined group of access lines or from a directory number outside of the group. In another service, the end user specifies, by the calling directory number, the ringing pattern appearing at the NI of the CI terminating the call. patterns 1 through 4 in table 1 should be used for these services. 5.8 Automatic callback Automatic callback permits a calling CI that encounters a busy called access line to be notified by a distinctive ringing pattern when the called line becomes idle. A distinctive alerting pattern permits the automatic callback call to be distinguished from a normal incoming call. Once the automatic callback subscriber answers the call, a call set-up attempt is made toward the original called party that is alerted with the ringing usually applied (usually pattern 1). On access lines with automatic callback, pattern 1 in table 1 will usually be applied at the NI for normal incoming calls. Pattern 2 or pattern 3 should be applied to the line to indicate automatic callback. 5.9 Automatic recall Automatic recall is a supplemental feature on switched access lines that allows an end user to automatically call back the directory number associated with the last calling CI without having to know the directory number. If the last calling line is busy when automatic recall is activated by an end-user, the call will be queued by the network until both access lines are idle. When both lines become idle, a distinctive ringing pattern will be applied to the CI that activated automatic recall. The distinctive ringing pattern permits the automatic recall to be distinguished from a normal incoming call. Once the automatic recall subscriber answers the call, a call set-up attempt is made toward the last calling line, which is alerted with the ringing usually applied (usually pattern 1). On access lines with automatic recall, pattern 1 in table 1 will usually be applied to the NI for normal incoming calls. Pattern 2 or pattern 3 should be applied to the line to indicate automatic recall Call-forwarding ring reminder Certain call-forwarding services, such as variable call-forwarding and selective call-forwarding, have an associated ring reminder feature. The purpose of the ring reminder signal is to remind the customer that a call-forwarding feature is activated. If the ring reminder feature is activated, the network will apply a unique ringing signal, called a ring reminder signal, to alert the CI that a call has been received and is being forwarded. In such a case, the network does not establish a terminating connection to the called number. Therefore, if the CI goes off-hook during or after the ring reminder signal, the network will treat this as an originating service request not a called-party answer signal. Pattern 5 in table 1 is the ring reminder signal. When call forwarding is not activated, pattern 1 is usually applied to the NI for normal incoming calls.

10 Pattern Table 1 Distinctive ringing pattern objectives at the NI Cadence 2 s on 4 s off Minimum Nominal Maximum single burst

11 6 Distinctive alerting by call-waiting tone patterns 6.1 General description Some supplemental services provided by the network use distinctive alerting both by distinctive ringing signals and by distinctive call-waiting (CW) tones. A call-waiting feature infor a busy CI, by a single burst of tone or a distinctive CW tone pattern, that another call is waiting. 6.2 Characteristics of the CW tone and distinctive CW tone The CW tone has a nominal frequency of 440 Hz that is generated in a single nominal 0.3 s burst. A distinctive CW tone follows a prescribed pattern (cadence). The characteristics of the CW tone and the distinctive CW tones are provided in T Open switch intervals Open switch intervals (OSIs) are caused when circuits are rearranged within a switching system. An OSI appears to a CI as an open loop condition (no dc voltage between tip and ring). OSIs may be as as 350 in length. The silent intervals in some distinctive ringing patterns are less than 350 in length. In these cases, there may be no dc voltage applied at the NI during the silent interval. For er silent intervals, there may be an interval of up to 350 during which no DC voltage is applied at the NI.

12 Annex A (informative) Distinctive ringing patterns produced by the network The distinctive ringing patterns produced by the network consist of a repeated grouping of one to three bursts of ringing. The ringing bursts can be or. The bursts of ringing are separated by a relatively silent interval ( intra-group ) while the groups of ringing bursts are separated by a er silent interval ( inter-group ). Table A.1 gives ranges of the duration of the ringing bursts, the ringing bursts, the intra-group silent interval, and the inter-group silent interval currently produced by the network. The objectives provided in table 1 were established to enhance the ability of CI equipment to detect the distinctive ringing patterns and to help ensure compatibility of distinctive-ringing supplemental services with other supplemental services. It should be noted that the use of some of the ringing patterns given in this annex may preclude the proper operation of some supplemental services dependent on the transmission of signals during the est silent interval. Different patterns of distinctive ringing are produced by combining and ringing bursts into groups of one to three bursts of ringing. Table A.2 lists the distinctive ringing patterns currently produced by the network. These distinctive ringing patterns are in addition to the standard ringing pattern of nominal two-seconds ringing followed by a nominal four-second silent interval. This listing may not be exhaustive. Four distinctive ringing patterns are commonly used with supplemental services using distinctive ringing. Nominal, minimum, and maximum values for the duration of the ringing bursts and silent intervals for these patterns are given in table A.3. Additional patterns are sometimes employed in the network for distinctive alerting, using the cadences in table A.2, by varying the duration of alerting intervals within the limits defined in table A.1. For example, two distinctive ringing patterns can be derived from the cadence by using two 1-s ringing intervals or two 1.5-s ringing intervals. The patterns in table A.3 are employed throughout the US and Canada. However, there are some additional distinctive ringing patterns currently produced by the network, which it is believed are primarily employed in Canada. These patterns are listed in table A.4.

13 Table A.1 Distinctive ringing interval durations Interval Minimum Maximum Short ringing burst Long ringing burst Intra-group silent interval Inter-group silent interval Table A.2 Distinctive ringing patterns Number of ringing bursts in pattern 1 Short 2 3 Cadence of pattern Short Short Long Long Short Short Long Long Pattern Table A.3 Interval durations of the more commonly used distinctive ringing patterns Cadence Minimum Nominal Maximum Note NOTE One single ringing burst.

14 Table A.4 Additional distinctive ringing patterns bursts in pattern Pattern Cadence 2 3 Nominal duration NOTE The nominal duration of the ringing intervals is usually either 1000 or 1500.

15 Annex B (informative) Bibliography T , and T1.209a-1995 Supplement, Telecommunications Operations, administration, maintenance, and provisioning (OAM&P) Network tones and announcements T , Network-to-Customer Installation Interfaces - - Analog Voicegrade Switched Access Lines Using Loop-Start or Ground-Start Signaling With Line-Side Answer Supervision Feature T , Network-to-Customer Installation Interfaces - Analog Switched Access Lines with the Calling Number Delivery, Calling Name Delivery, or Visual Message- Waiting Indicator Feature T , Network-to-Customer Installation Interfaces - Analog Voicegrade Switched Access Lines with Call Waiting, Distinctive Call Waiting, or Calling Identity Delivery on Call Waiting Feature