1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0600401.2006(R2011) Network to Customer Installation Interfaces Analog Voicegrade Switched Access Lines Using Loop-Start and Ground-Start Signaling ATIS is the leading technical planning and standards development organization committed to the r
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5、it . AMERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards
6、Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made towards their
7、 resolution. The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards.
8、The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American Na
9、tional Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards
10、 Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer includes T1.401a-2000
11、and T1.401b-2002) American National Standard for Telecommunications NETWORK TO CUSTOMER INSTALLATION INTERFACES ANALOG VOICEGRADE SWITCHED ACCESS LINES USING LOOP-START AND GROUND-START SIGNALING Secretariat Alliance for Telecommunications Industry Solutions Approved July 26, 2006 American National
12、Standards Institute, Inc. Abstract This standard provides requirements for loop-start and ground-start signaling for the analog voicegrade interface between carrier switched access lines and customer installations. These requirements are intended to assist carriers, manufacturers, and users of produ
13、cts to be used in the switched network to understand the characteristics of the existing networks. This standard is a revision and compilation of T1.401-2000 and its supplements T1.401a-2000 and T1.401b-20002, which it replaces in its entirety. ATIS-0600401.2006 ii FOREWORD The information contained
14、 in this Foreword is not part of this American National Standard (ANS) and has not been processed in accordance with ANSIs requirements for an ANS. As such, this Foreword may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requir
15、ements necessary for conformance to the Standard. The Alliance for Telecommunication Industry Solutions (ATIS) serves the public through improved understanding between carriers, customers, and manufacturers. The Network Interface, Power, and Protection Committee (NIPP) - formerly T1E1 - develops and
16、 recommends standards and technical reports. The standards and technical reports are related to power systems, electrical and physical protection for the exchange and interexchange carrier networks, and interfaces associated with user access to telecommunications networks. ANSI guidelines specify tw
17、o categories of requirements: mandatory and recommendation. The mandatory requirements are designated by the word shall and recommendations by the word should. Where both a mandatory requirement and a recommendation are specified for the same criterion, the recommendation represents a goal currently
18、 identifiable as having distinct compatibility or performance advantages. This standard is one of a series of network-to-customer installation interface standards originally developed by Technical Subcommittee T1E1 of Accredited Standards Committee T1, Telecommunications. This standard is intended t
19、o be a living document, subject to revision and updating as warranted by advances in network and equipment technology. This standard provides the requirements associated with analog voicegrade switched access lines that use loop-start or ground-start signaling. This standard will be useful to those
20、engaged in the provisioning or operation of telecommunications equipment or services that share a boundary at the Network Interface (NI). Compliance with this standard should provide interface compatibility in most installations, but this standard does not guarantee compatibility or acceptable perfo
21、rmance under all operating conditions. In some cases, location-oriented options are needed to ensure compatibility at the NI. This need for options is imposed by significant differences between various network elements. This standard has six annexes. Annexes A, B, C, D, E, and F are informative. The
22、 informative annexes and footnotes are not considered a part of this standard. This is the fourth issue of this standard and it supersedes American National Standard T1.401-2000 in its entirety. Some of the revisions were editorial in nature, that is, they are intended to provide information or to i
23、mprove clarity. The following technical revisions were made: A description of test signals used for measuring line characteristics was added to Annex A. Amendments T1.401a-2001 and T1.401b-2002 were merged into this document. Suggestions for the improvement of this standard are welcome. They should
24、be sent to the Alliance for Telecommunications Industry Solutions, NIPP Secretariat, 1200 G Street, NW, Suite 500, Washington, DC 20005. At the time of initiation or issuance of the letter ballot for this document, NIPP, which was responsible for its development, had the following roster: R. Townsen
25、d, NIPP Chair E. Eckert, NIPP Vice-Chair S. Carioti, ATIS Disciplines S. Barclay, ATIS Secretariat C. Underkoffler, ATIS Chief Editor M. Darveau, NIPP Technical Editors Organization Represented Name of Representative Actelis Networks Inc. Ishai Ilani ADC Telecommunications Inc. Bob Kroninger Dieter
26、Nattkemper (Alt.) ADTRAN Inc. Arlynn Wilson Richard Goodson (Alt.) Aktino, Inc. Ray Nagele Michail Tsatsanis (Alt.) Alcatel USA Inc. Ken Biholar J. Lane Moss (Alt.) ASSIA Inc. Peter Silverman Wonjong Rhee (Alt.) Organization Represented Name of Representative AT generally with a frequency range of a
27、bout 300 to 3000 Hz. The term is also used to describe a signal with a frequency range of about 300 to 3000 Hz. 7The ringer type indicates the ringing frequencies for which the REN is valid. ATIS-0600401 7 3.2 Abbreviations, Acronyms, otherwise, it is called a switched access line. The network switc
28、hing systems and transmission facilities used to provide switched access lines affect the requirements of this standard. A transmission facility connects the local switching system to the NI. There are two types of loop-start and ground-start switched access lines: Two-wire. Four-wire. 5.1 Two-WireS
29、witched Access Lines At the NI, a two-wire access line appears as two conductors commonly called tip (T) and ring (R). The requirements and recommendations in this standard are written using two-wire access line terminology. 5.2 Four-Wire Switched Access Lines At the NI, a four-wire access line appe
30、ars as four conductors commonly called T, R, T1, and R1. The two-wire loop-start and ground-start requirements in this standard shall apply to four-wire NIs. The four-wire lead designations and their electrical functions are illustrated in Figure 1 and are defined as follows: The leads designated T
31、and R at the NI shall be used for transmitting voicegrade signals toward the network. The leads designated T1 and R1 at the NI shall be used for receiving voicegrade signals from the network. The lead derived by the CI from the T and R pair shall provide the same electrical function as the tip lead
32、for two-wire Nls. This lead is commonly designated the A lead. The lead derived by the CI from the T1 and R1 pair shall provide the same electrical function as the ring lead for two-wire Nls. This lead is commonly designated the B lead. ATIS-0600401 10 B lead A lead NIVoiceband signalVoiceband signa
33、lT1R1TRT R Network CI (four-wire) NOTE Lead designations at the NI conform to the FCC Rules and Regulations, Part 68, Subpart A. A B Figure 1 - Four-Wire Network Interface 5.3 Switched Access Line Loop Current-Feed Interfaces Two types of loop current-feed interfaces are used in the network: 1. Grou
34、nded: One conductor of the access line is connected through a 0 to 5 Volt dc offset to ground. This is often called a conventional battery-feed circuit. 2. Ground-referenced: Neither conductor of the interface is directly grounded. A high impedance ground-reference circuit is connected between one c
35、onductor of the interface and ground. This is often called a floating battery-feed circuit. However, some ground reference is required to ensure that both conductors of the interface are non-positive with respect to ground. 5.3.1 Grounded Loop Current-Feed Interfaces Figure 2 shows a network grounde
36、d loop current-feed interface. When used to provide loop-start services, a network grounded loop-current feed interface connects the tip conductor to the network equipment ground (C closed; D open) and the ring conductor to a dc voltage negative with respect to ground. However, outside plant mainten
37、ance activities and feature usage (e.g., line side answer supervision) may reverse these voltages either temporarily or permanently; therefore, connection of ATIS-0600401 11 one specific conductor of a loop-start interface to network ground cannot be assured. When used to provide ground-start servic
38、es, a network grounded loop-current interface connects a dc voltage negative with respect to ground to the ring conductor and connects network ground to the tip conductor when required. Voiceband signals transmission path C Access networkRinging detector Voice grade equip-ment NICI Network switching
39、 system or carrier systemT RDial Switchhook Switchhook Current limiter Current limiter Current detector dc voltage sourceRinging, call progress tone signals, dc voltage On-hook, off-hook, address signalsSee notes Network ground Ground - reference circuit D Figure 2 - Operation of Loop-Start Signalin
40、g Simplified Schematic NOTE - C is closed and D is open for grounded loop current-feed interfaces, and D is closed and C is open for ground-referenced loop current-feed interfaces. 5.3.2 Ground-Referenced Loop Current-Feed Interfaces Figure 2 (C open; D closed) shows a ground-referenced loop current
41、-feed interface. A ground-referenced loop current-feed interface connects one conductor of the interface to ground through a high-impedance ground-reference circuit to ensure that both conductors of the interface are non-positive with respect to ground. ATIS-0600401 12 6 LOOP-START SIGNALING 6.1 Gen
42、eral This clause specifies loop-start signaling parameters between the network and the CI at the NI. Loop-start signaling is the most commonly used signaling method for analog voicegrade switched access lines. The main advantages of loop-start signaling are its simplicity and low cost. Loop-start si
43、gnaling has the following key disadvantages: No disconnect signal is provided to either the originating or the terminating NI when either CI goes to the on-hook state. At some NIs, the network opens the loop (no voltage between tip and ring) as it reconfigures to the idle state. However, these open
44、intervals are not of a fixed duration, never appear at some Nls, and should not be relied upon as disconnect signals. If one CI remains in the off-hook state after the other CI disconnects, the network may return dial tone to that Cl. The network may seize a terminating CI for up to 4.45 seconds pri
45、or to applying a ringing signal to the terminating NI. 6.2 Principle of Loop-Start Operation Figure 2 shows the principle of operation of loop-start signaling. It does not represent the actual implementation of any network loop current-feed interface. The CI appears as a very high tip-to-ring resist
46、ance during the idle (on-hook) state, and thus, a virtual dc open-circuit condition exists at the NI. To originate a service request, the CI applies an off-hook signal to the NI by closing the switch hook contacts (see Figure 2), which provides a loop closure termination with a low tip-to-ring resis
47、tance. The low resistance causes a dc loop current to flow in the tip and ring conductors. The network detects this current to determine that the CI went to the off-hook state. The name loop-start signaling comes from the use of a CI loop closure to initiate a service request. The process by which t
48、he network monitors the CI status is called dc loop supervision. The request for service initiated by the originating CI is called a seizure. The network responds to a CI seizure by applying a dial-tone signal that is superimposed on the dc current flowing in the loop circuit. To alert the CI to a t
49、erminating (incoming) call (while the CI is in the idle state), the network applies an alerting signal to the NI. The CI answers the call by applying an off-hook signal to the NI. The component of the alerting signal recognizable by the CI is an ac ringing signal, superimposed on a dc signal (see 6.8.2). The alerting signal typically consists of nominal 2-second ac ringing intervals separated by nominal 4-second silent intervals. As a result, after allowing for timing tolerances, an NI can be seized by the network for as long as 4.45
