ÿWPCL ûÿ2BJ|xÐ ÐÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÐ(€Ø ¸)x-ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌÐÐ °°È  ÐÐ Å°6Ø'°6Ø'Å ÐÕ‚†Ð ÐÑ Âx„|ü@Ž Ñ  à ÃFascicle VI.14 © Rec. Q.1101Ä Ä‚ÕÕßIÑ Âx„|ü@Ž Ñ Ã ÃFascicle VI.14 © Rec. Q.1101Ä Ä ßÕÐ È ÈX Ðà ÃRecommendation Q.1101Ä Ä Áà°?Áà ÃGENERAL REQUIREMENTS FOR THE INTERWORKING OFÄ Äƒ Áà°EÁà ÃTHE TERRESTRIAL TELEPHONE NETWORKÄ Äƒ Áà°FÁà ÃAND INMARSAT STANDARD A SYSTEMÄ Äƒ à Ã1Ä ÄÁÐÁà ÃIntroductionÄ Ä Ð Ð1.1ÁÐÁThe purpose of this Recommendation is to define the general interworking requirements between the telephone network and the INMARSAT Standard A system. Ð Ð1.2ÁÐÁIn order to support automatic working between subscribers in the public telephone service and telephone subscribers to the maritime mobile©satellite service, it is necessary that the interface between the terrestrial telephone network and the maritime satellite system be defined. Ð Ð1.3ÁÐÁIt should be possible to interface the maritime©mobile satellite system with any signalling system standardized by the CCITT for automatic working. In order to facilitate the preparation of the interworking equipment, and also aiming at the international standardization of the service, this Recommendation lists several basic interworking requirements common to all signalling systems. 1.4ÁÐÁMore specific interworking requirements applicable to System No. 5 are given in Recommendation Q.1103 and System R2 are given in Recommendation Q.1102. Ð Ð1.5ÁÐÁA brief description of the INMARSAT Standard A system is given in Annex A. SDL descriptions of incoming and outgoing signalling procedures for the INMARSAT system are given in Annexes B and C respectively. Ð Ð1.6ÁÐÁInterworking between the telephone network/ISDN and other INMARSAT systems is given in separate Q©Series Recommendations. à Ã2Ä ÄÁÐÁà ÃMaritime satellite switching centreÄ Ä Ð ÐÁÐÁFor the purpose of this Recommendation the term Maritime Satellite Switching Centre (MSSC) is used to indicate the interworking point between the terrestrial telephone network and the maritime satellite system. The maritime satellite switching centre (MSSC) may be located at the antenna site of the coast earth station [1] and operate as an independent international switching centre connected to one or more international switching centres (ISCs) or national switching centres, or it may be remote as a supplement to or as a part of an international switching centre. à Ã3Ä ÄÁÐÁà ÃList of general Series Q RecommendationsÄ Ä Ð€ÐÁÐÁDue regard should be paid to the following general Series Q Recommendations: ÐÐ ÁÐÁ©Á( ÁQ.11, Q.11ÃÃÓÓÃÃwÄÄÄÄbisÃÃwÄÄ, Q.11ÃÃÃÃwÄÄÄÄterÃÃwÄÄ, and Q.12, Q.13, numbering and routing plan ÁÐÁ©Á( ÁQ.14, means of controlling the number of satellite links ÁÐÁ©Á( ÁQ.15 through Q.22, general Recommendations ÁÐÁ©Á( ÁQ.23, technical features of push©button telephone sets ÁÐÁ©Á( ÁQ.25, splitting arrangement ÁÐÁ©Á( ÁQ.26 through Q.33, miscellaneous provisions ÁÐÁ©Á( ÁQ.35, tones of national signalling systems ÁÐÁ©Á( ÁQ.40 through Q.45, transmission characteristics ÁÐÁ©Á( ÁQ.102, facilities provided in international automatic working ÁÐÁ©Á( ÁQ.103, numbering used ÁÐÁ©Á( ÁQ.104, language digit or discriminating digit ÁÐÁ©Á( ÁQ.105, national (significant) number ÁÐÁ©Á( ÁQ.106, the sending©finished signal ÁÐÁ©Á( ÁQ.107, sending sequence of forward©address information ÁÐÁ©Á( ÁQ.107ÃÃÃÃwÄÄÄÄbisÃÃwÄÄ, analysis of forward©address information for routing ÁÐÁ©Á( ÁQ.109, transmission of the answer signal ÁÐÁ©Á( ÁQ.112 through Q.114, transmission clauses ÁÐÁ©Á( ÁQ.115, control of echo suppressors ÁÐÁ©Á( ÁQ.116 through Q.118ÃÃÃÃwÄÄÄÄbisÃÃwÄÄ, abnormal conditions. à Ã4Ä ÄÁÐÁà ÃSending sequence of numerical (or address) signalsÄ Ä 4.1ÃÃÃÃwÄÄÄÄÁÐÁCalls toward ship earth stationÃÃwÄÄ [2]ÃÃÃÃwÄÄÄÄ (shore©to©ship)ÃÃwÄÄ Ð ÐÁÐÁIn most cases the MSSC will not need the information contained in the S©digit of the country code 87S. In this situation the sequence of forward©address information sent to the MSSC should be as for a terminal international call. Ð ÐÁÐÁCases may arise where an MSSC requires the S©digit to distinguish between ocean areas, satellite systems or VHF/UHF vs. satellite. In this situation the sequence of forward©address information should be as for an international transit call, i.e. the sequence includes the country code 87S. ЀРÐÐ4.2ÃÃÃÃwÄÄÄÄÁÐÁS©digitÃÃwÄÄ Ð ÐÁÐÁIt is a matter for the terrestrial subscriber to choose the proper S©digit and the MSSC to be used will be decided by the outgoing country. (For technical reasons accounting between Administrations should be performed on the basis of only 87S.) ЀРÐÐ4.3ÃÃÃÃwÄÄÄÄÁÐÁCalls from ship earth station (ship©to©shore)ÃÃwÄÄ Ð ÐÁÐÁThe desired MSSC is selected at the ship earth station by procedures within the maritime satellite system. After the dialling tone has been provided to the subscriber, he will dial a prefix followed by the full international telephone number required, whether or not the MSSC is located in the required subscriber's country (see also Recommendation Q.11ÃÃÃÃwÄÄÄÄquaterÃÃwÄÄ). Ð ÐÁÐÁThe prefix must be suppressed by the MSSC since it is only required for internal routing in the MSSC. Ð ÐÁÐÁFor calls to subscribers in the MSSC country, the country code should also be suppressed by the MSSC. Ð ÐÁÐÁA discriminating digit must be inserted by the MSSC according to Recommendation Q.104. ЀРÐÐ4.4ÃÃÃÃwÄÄÄÄÁÐÁOperator servicesÃÃwÄÄ Ð ÐÁÐÁThe desired MSSC is selected at the ship earth station by procedures within the maritime satellite system. After the dialling tone has been provided to the subscriber, he will dial a two digit prefix, possibly followed by a 1, 2 or 3 digit country code, to identify the type of operator required (see Recommendation Q.11ÃÃÃÃwÄÄÄÄquaterÃÃwÄÄ). Ð ÐÁÐÁThe MSSC could then convert the received dialling information as required for setting up the terrestrial connection to the operator. ЀРÐÐ4.5ÃÃÃÃwÄÄÄÄÁÐÁSpecial service terminationsÃÃwÄÄ Ð ÐÁÐÁThe desired MSSC is selected at the ship earth station by procedures within the maritime satellite system. After the dialling tone has been provided to the subscriber, he will dial a two digit prefix possibly followed by other digits to identify the type of special service termination required. (See Recommendation Q.11ÃÃÃÃwÄÄÄÄquaterÃÃwÄÄ.) The MSSC should convert the received dialling information as required for setting up the terrestrial connection. à Ã5Ä ÄÁÐÁà ÃSpecial requirements related to setting©up and clearing of automatic callsÄ Ä Ð€Ð5.1ÃÃÃÃwÄÄÄÄÁÐÁSetting©up time for shore originated callsÃÃwÄÄ ÐÐ Ð ÐÁÐÁThe setting©up time for shore originated calls should be as short as possible. If the MSSC has not been able to establish the connection within a period of 20 seconds after receipt of all address digits, a congestion indication should be returned. ÐÐ Ð ÐÃÃÃÃwÄÄÄÄÁÐÁNoteÃÃwÄÄ © In maritime satellite systems the setting©up time is not controlled by each individual MSSC but may depend on the overall traffic load in the system and on the assignment procedure used. For several reasons the setting©up time of the radio path is likely to be longer than the setting©up time of the subscriber connection in terrestrial ЀÐsystems. ÐРЀР5.2ÃÃÃÃwÄÄÄÄÁÐÁTransmission of answer signalÃÃwÄÄ ÐÐ Ð Ð5.2.1Á( ÁWhen the maritime satellite switching centre (MSSC) detects the answer signal from the maritime satellite system, the MSSC must remove the ringing tone, through©connect the circuit and return the answer signal as soon as possible to the terrestrial switching centre. ÐÐ Ð ÐÁÐÁPrecautions should be taken at the MSSC to avoid interpreting an interruption of the satellite link as an answer signal. Ð Ð5.2.2Á( ÁFor ship originated calls the maritime satellite system should preferably include provisions for transferring the answer signal to the ship earth station. ЀР5.3ÃÃÃÃwÄÄÄÄÁÐÁSeizure of a terrestrial circuit from the MSSCÃÃwÄÄ ÐÐ Ð ÐÁÐÁThe maritime satellite switching centre should not seize a terrestrial circuit before each of ЀÐthe following conditions has been met: ÐÐ ÁÐÁ©Âà( Âthe satellite channel has been assigned;ÆÆ ÁÐÁ©Âà( Âthe continuity of the satellite channel has been verified;ÆÆ Ð ÐÁÐÁ©Âà( Âall digits necessary for routing decision by the maritime satellite switching centre have been received.ÆÆ Ð€Ð 5.4ÃÃÃÃwÄÄÄÄÁÐÁClear©back conditionsÃÃwÄÄ ÐÐ Ð Ð5.4.1Á( ÁThe clear©back/re©answer sequence may not apply for shore originated calls, in which case the satellite link will be released when a clear©back signal is detected at the maritime satellite switching centre from the satellite link, without waiting for a clear©forward signal from the terrestrial network. ÐÐ Ð ÐÁÐÁPrecautions should be taken either at the MSSC or at the ship earth station in order to avoid ЀÐunintentional clearing. ÐÐ Ð Ð5.4.2Á( ÁFor ship originated calls the normal clear©back procedures should apply (see ЀÐRecommendation Q.118). ÐРЀР5.5ÃÃÃÃwÄÄÄÄÁÐÁClear©forwardÃÃwÄÄ ÐÐ Ð ÐÁÐÁWhen detecting a clear©forward from the satellite link, the MSSC should immediately pass the ЀÐclear©forward signal into the terrestrial network. ÐÐ Ð ÐÁÐÁWhen detecting a clear©forward from the terrestrial network, the release guard (and clearing) ЀÐsequence should follow the procedures defined for the signalling system used. ÐРЀР5.6ÃÃÃÃwÄÄÄÄÁÐÁSplitting arrangementÃÃwÄÄ ÐÐ Ð ÐÁÐÁWhen in©band signalling is used over the satellite link for setting©up and clearing of the link, a splitting arrangement shall be provided in order to avoid that signalling tones are passed into the terrestrial network. The splitting time shall be less than ЀÐ20 ms. ÐÐ Ð ÐÁÐÁIn order to protect the maritime satellite system from line signals used on terrestrial signalling systems, it should be observed that such signalling tones passing through splitting arrangements in the terrestrial network may have a maximum duration of 50 ms. à Ã6Ä ÄÁÐÁà ÃAudible tones sent by the MSSCÄ Ä Ð ÐÁÐÁTones sent by the maritime switching centre (MSSC) should have the following characteristics: ÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÐ(€Ø x¸)x-ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌРЀРРÐÐÐÁÐÁDial tone:ÁØ Á x!Â425 Hz (1.5 seconds maximum, minimum is determined by receipt of first dial digit)ÆÆ Ð ÐÁÐÁRinging tone:ÁØ Á x!Â425 Hz (1 second on, 4 seconds off, immediate ringing)ÆÆ ÁÐÁBusy tone:ÁØ Á x!Â425 Hz (1/2 second on, 1/2 second off)ÆÆ ÁÐÁCongestion tone:Â(x!Â425 Hz (1/4 second on, 1/4 second off)ÆÆ ÁÐÁSpecial information tone:Âðx!Âas defined in Recommendation Q.35.ÆÆ ÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÐ(€Ø ¸)x-ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌÐЀРÐÐ Ð ÐÃÃÃÃwÄÄÄÄÁÐÁNoteÃÃwÄÄ © The dial tone is given as 1.5 seconds pulse in order to avoid subscribers' confusion due to the two©way transmission delay of 0.5 seconds. If the normal continuous tone with interruption after the receipt of the first digit was used, the delay would cause the tone to stay on after entry of the first digit. à Ã7Ä ÄÁÐÁà ÃControl of echo suppressorsÄ Ä Ð ÐÁÐÁSince all calls to and from a ship earth station will include a satellite link, appropriate actions must be taken to insert an incoming or outgoing half©echo suppressor at the MSSC or at an international exchange closer to the terrestrial subscriber. The ship earth station will connect to the satellite link on a 4©wire basis or will be provided with the equivalent of a half©echo suppressor. In order to reduce the analysis and control requirements at the MSSC it may prove convenient to carry out all echo suppressor control at one of the international exchanges rather than at the MSSC. This is most easily achieved by fitting permanent half©echo suppressors at the ISC end of each MSSC©ISC circuit. In any case the overall echo control requirements are the same as specified in Recommendation Q.115. ÐÐ 7.1ÃÃÃÃwÄÄÄÄÁÐÁTerrestrial signalling systems with signals for control of echo suppressorsÃÃwÄÄ ÐÐ7.1.1ÃÃÃÃwÄÄÄÄ ÐÐÁÐÁShip original callsÃÃwÄÄ Ð ÐÁÐÁThe MSSC should send an echo suppressor indicator informing transit centres or incoming centres ЀÐwhether or not an incoming half©echo suppressor should be included. ÐÐ Ð ÐÁÐÁInsertion of an incoming half©echo suppressor will always be requested if the MSSC does not ЀÐcarry out echo suppressor control. ÐÐ ÐÐ7.1.2ÃÃÃÃwÄÄÄÄ ÐÐÁÐÁShore originated callsÃÃwÄÄ Ð ÐÁÐÁThe MSSC will decide whether or not to insert an outgoing half©echo suppressor depending on the received echo suppressor indicator. If echo control is not performed at the MSSC, the echo suppressor indicator will always inform the MSSC that an outgoing half©echo suppressor has already been included. ÐÐ Ð ÐЀÐ7.2ÃÃÃÃwÄÄÄÄÁÐÁTerrestrial signalling systems without signals from control of echo suppressorsÃÃwÄÄ ÐÐ Ð ÐÁÐÁWhen signals for the control of echo suppressors are not available on the particular terrestrial route, significant advantage is to be gained by carrying out the echo suppressor control at the international exchange. In any case the following rules should ЀÐbe observed: ÐÐ ÐÐ7.2.1ÃÃÃÃwÄÄÄÄ ÐÐÁÐÁShip originated callsÃÃwÄÄ Ð ÐÁÐÁa)Âh( ÂWhen the terrestrial connection between the outgoing ISC, (or MSSC) and the incoming ISC (or national incoming switching centre) does not normally require the use of echo suppressors, the outgoing ISC (or MSSC) should enable (or insert) an incoming half©echo suppressor associated with the satellite link.ÆÆ Ð ÐÁÐÁb)Âh( ÂWhen the terrestrial connection between the outgoing ISC (or MSSC) and the incoming ISC (or national incoming switching centre) normally requires the use of echoÔ ƒ1Ô suppressors, the outgoing ISC (or MSSC) should disable (or should not insert) any half©echo suppressors associated with either the satellite link or the terrestrial link.ÆÆ ÐÐ7.2.2ÃÃÃÃwÄÄÄÄ ÐÐÁÐÁShore originated callsÃÃwÄÄ Ð ÐÁÐÁa)Âh( ÂWhen the international connection between the outgoing ISC and the incoming ISC (or MSSC) does not normally require the use of echo suppressors, the incoming ISC (or MSSC) should enable (or insert) an outgoing half©echo suppressor associated with the satellite link.ÆÆ Ð ÐÁÐÁb)Âh( ÂWhen the international connection between the outgoing ISC and the incoming ISC (or MSSC) normally requires the use of echo suppressors, the incoming ISC (or MSSC) should disable (or should not insert) any half©echo suppressors associated with either the satellite or terrestrial link.ÆÆ Ã Ã8Ä ÄÁÐÁà ÃHandling of group callsÄ Ä 8.1ÃÃÃÃwÄÄÄÄÁÐÁGeneralÃÃwÄÄ Ð ÐÁÐÁA group call is a simultaneous call to a given group of ships. Such calls are identified by the following international number: Áà°OÁ87S0XÃÃ2ÄÄXÃÃ3ÄÄ...XÃÃkÄă Ð Ðwhere the first digit of the ship station number has the fixed value 0. The remaining digits determine which group of ships is being addressed. Ð ÐÁÐÁFacilities for originating group calls from operators either in the MSSC country or another country may be readily made available by permitting such calls only when the Z digit is a language digit. Group calls originating from ordinary telephone subscribers should not be permitted so long as calling line identification is not available. 8.2ÃÃÃÃwÄÄÄÄÁÐÁBarring at the ISC of originÃÃwÄÄ Ð ÐÁÐÁIn order to avoid setting up of the international chain for unauthorized group calls from ordinary subscribers, barring of such calls should, as a general rule, be done at the ISC of origin. 8.3ÃÃÃÃwÄÄÄÄÁÐÁBarring at the MSSCÃÃwÄÄ Ð ÐÁÐÁBarring should also be provided at the MSSC in order to reject group call attempts from ships or from subscribers in countries where barring at the outgoing ISC is not possible. à Ã9Ä ÄÁÐÁà ÃAvoiding two or more satellite links in tandemÄ Ä 9.1ÃÃÃÃwÄÄÄÄÁÐÁShore originated callsÃÃwÄÄ Ð ÐÁÐÁThe country code 87S should be analysed at all transit centres where the call may either be routed on a circuit containing a satellite link or on a circuit not containing a satellite link. The latter circuit should always be chosen (see Recommendation Q.14). 9.2ÃÃÃÃwÄÄÄÄÁÐÁShip originated callsÃÃwÄÄ Ð ÐÁÐÁIf the signalling system provided between the MSSC and the terrestrial network contains signals which may be used to indicate that one satellite link is included, such signals should be used. Ð ÐÁÐÁIf the signalling system does not contain such signals, the outgoing ISC should avoid forwarding the call on an outgoing circuit which includes a satellite link. If, however, the signalling system employed between the outgoing ISC and the next ISC in the connection contains such signals, the outgoing ISC should insert the required information. The outgoing ISC could base its procedure upon incoming route identification. à Ã10Ä ÄÁÐÁà ÃOperator assistance for semi©automatic shore originated callsÄ Ä Ð ÐÁÐÁIf code 11/12 assistance facilities are not provided at the MSSC, then arrangements should be made to intercept such calls at the preceding ISC and route them to an appropriate operator. Ð ÐÁÐÁIt may be advantageous for Administrations to provide a publicized number (e.g. C12XXXX) for specialized assistance on calls to the maritime network. Áà°RÁANNEX Aƒ Áà°UÁƒ Áà°HÁ(to Recommendation Q.1101)ƒ Áà°UÁƒ Áà°EÁà ÃBrief description of the INMARSATÄ Äƒ Áà°MÁà ÃStandard A systemÄ Äƒ A.1ÃÃÃÃwÄÄÄÄÁÐÁIntroductionÃÃwÄÄ Ð ÐÁÐÁThis annex describes the signalling in the INMARSAT Standard A system in a multiple Maritime Satellite Switching Centre (MSSC) configuration, i.e., there is more than one MSSC serving an ocean region. Automatic call set©up and clearing are illustrated below. For calls which cannot be completed, the subscriber will receive from the MSSC or the terrestrial network the proper audible tone which describes the call status (i.e., busy tone, congestion tone). A.2ÃÃÃÃwÄÄÄÄÁÐÁSystem configurationÃÃwÄÄ Ð ÐÁÐÁThe INMARSAT system is composed as shown in Figure A©1/Q.1101. Only the components required for interfacing the telephone network are shown. There are additional interfaces similar to the MSSC for interfacing the telex network and the international public data network. ÁÐÁThe purpose of the MSSC is defined in ÀÀ 2 of the Recommendation. Ð ÐÁÐÁThere is one operating Network Coordination Station (NCS) in each ocean area (there may in addition be one or more standby NCSs per ocean area). The main functions of the NCS are as follows. Ð ÐÁÐÁThe ship earth stations can only monitor one calling channel in the shore©to©ship direction. This calling channel, denoted as the common assignment channel, is transmitted by the NCS. Each coast earth station transmits its own calling channel which is monitored by the NCS for relaying signalling messages from a coast earth station to a ship. Ð ÐÁÐÁThe NCS also performs all assignment of telephone channels on a call©by©call basis and monitors the actual use of the channels for maintenance purposes. The NCS keeps an up©dated list of all busy ships in the ocean area. If a coast earth station calls a busy ship, the NCS may thus return a ship busy indication to the calling coast earth station on the common assignment channel. ÁÐÁThe procedures are further described below. A.3ÃÃÃÃwÄÄÄÄÁÐÁShip earth station originated callsÃÃwÄÄ Ð ÐÁÐÁThe normal call set©up procedure for automatic call processing from a ship earth station is shown in Figure A©2/Q.1101. The ship earth station transmits an out©of©band request message which includes the type of call desired, the identify of the MSSC through which the terminal wishes to communicate and the identification number of the ship earthÔ ƒ1Ô station. * The NCS of an ocean area will normally be co©located with an MSSC of that area. Áà°MÁFIGURE A©1/Q.1101ƒ Áà°UÁƒ Áà°UÁƒ Áà°?Áà ÃComposition of the maritime satellite systemÄ Äƒ Áà°>Áà Ãfor interconnection with the telephone networkÄ Äƒ Ð ÐÁÐÁThe MSSC upon reacting to the receivedÃÃÃÃwÄÄÄÄ requestÃÃwÄÄ message, sends aÃÃÃÃwÄÄÄÄ Request for AssignmentÃÃwÄÄ message to the Network Coordination Station (NCS). The NCS receiving theÃÃÃÃwÄÄÄÄ request for assignmentÃÃwÄÄ message assigns a channel (frequency) and transmits this information in anÃÃÃÃwÄÄÄÄ assignmentÃÃwÄÄ message to both the MSSC and the ship earth station. Both the MSSC and ship earth station receive the ÃÃÃÃwÄÄÄÄassignmentÃÃwÄÄ message, automatically select the correct frequency, and initiate a continuity by transmitting a 2600 Hz tone. Ð ÐÁÐÁWhen continuity has been established, the MSSC sends a dial tone pulse to the ship earth station. The ship earth station subscriber then dials in the desired prefix, country code and national significant number followed by an end©of©selection signal. The signals are transferred as in band push button signals on the satellite link. Ð ÐÁÐÁThe MSSC proceeds to select a terrestrial trunk and follows the standard signalling sequences of the signalling system used towards the ISC (Figure A©2/Q.1101). The ringing tone from the terrestrial network is allowed to pass directly to the ship earth station subscriber. When the terrestrial party answers the call, the ISC passes the answer signal to the MSSC and the international connection is established. The answer signal, if implemented, may then be passed to the ship earth station 1ÃÃ)ÄÄ. A.4ÃÃÃÃwÄÄÄÄÁÐÁTerrestrial originated callsÃÃwÄÄ Ð ÐÁÐÁThe normal call set©up procedure for automatic call processing from the terrestrial network to a ship earth station is shown in Figure A©3/Q.1101. The ISC selects a circuit and sends the seizing signal and the mobile terminal identification digits to the MSSC in accordance with the procedures used in the terrestrial signalling system. The MSSC then sends aÃÃÃÃwÄÄÄÄ request©for©assignmentÃÃwÄÄ message to the NCS containing the ship earth station identity. The NCS responds by sending anÃÃÃÃwÄÄÄÄ assignmentÃÃwÄÄ message to both the MSSC and the ship earth station. The MSSC and the ship earth station activate their carriers and send a 2600 Hz tone. Upon receipt of the 2600 Hz tone from the ship earth station the MSSC interprets this as an address complete condition, sends the ringing tone to the terrestrial network and stops sending 2600 Hz to the ship earth station. When the operator or subscriber at the ship earth station answers, the ship earth station discontinues sending its 2600 Hz tone. Ð ÐÁÐÁThe MSSC recognizes the cutting of the 2600 Hz tone as an answer signal from the ship earth station and begins the answer sequence toward the ISC as shown in Figure A©3/Q.1101. ÁÐÁÃÃÃÃwÄÄÄÄNoteÃÃwÄÄ © If implemented. Áà°MÁFIGURE A©2/Q.1101ƒ Áà°UÁƒ Áà°DÁà ÃShip earth station originated callsÄ Äƒ Áà°MÁFIGURE A©3/Q.1101ƒ Áà°UÁƒ Áà°CÁà ÃTerrestrial originated automatic callÄ Äƒ A.5ÃÃÃÃwÄÄÄÄÁÐÁAutomatic clearing of callsÃÃwÄÄ Ð ÐÁÐÁWhether a telephone call originated from a ship earth station or from the terrestrial network, the MSSC, upon receiving a clear©forward signal, will begin to clear the call independently in each direction. Ð ÐÁÐÁThe MSSC, receiving a 2600 Hz clearing tone from a ship earth station will initiate clearing toward the terrestrial network in accordance with procedures defined for the signalling system used between the MSSC and the ISC. This applies to both clear©forward and clear©back from the ship earth station. Clearing will also be continued in the maritime satellite system independent of the terrestrial network. Ð ÐÁÐÁClearing initiated in the terrestrial network would be recognized by the MSSC receiving the appropiate clear©back or clear©forward signal. For clear©forward, the MSSC would continue clearing with normal terrestrial procedures and begin clearing the maritime satellite circuit. For clear©back from the terrestrial network, normal time©out supervision will take place and clear©forward will commence either after expiry of time©out or after receipt of a clear©forward from the ship, whichever happens first. Ð ÐÁÐÁAs examples of clearing sequences, Figure A©4/Q.1101 illustrates the clearing of a ship earth station originated call and Figure A©5/Q.1101 illustrates the clearing of a call originated in the terrestrial network. For a terrestrial originated call which has clearing initiated by the ship earth station, the satellite circuit is cleared after the MSSC recognizes the stopping of the ship earth station carrier. The terrestrial circuit is held until the end of release guard sequence as shown in Figure A©5/Q.1101. ÁÐÁSES = Ship earth station Áà°MÁFIGURE A©4/Q.1101ƒ Áà°AÁà ÃClearing sequences for ship earth stationÄ Äƒ Áà°MÁà Ãoriginated callsÄ Äƒ Áà°UÁƒ Áà°UÁƒ Áà°MÁFIGURE A©5/Q.1101ƒ Áà°<Áà ÃClearing sequences for terrestrial originated callsÄ Äƒ Áà°RÁANNEX Bƒ Áà°UÁƒ Áà°HÁ(to Recommendation Q.1101)ƒ Áà°UÁƒ Áà°UÁƒ Áà°=Áà ÃLogic procedures for incoming INMARSAT Standard AÄ Äƒ Áà°AÁà Ãsignalling system (ship originated call)Ä Äƒ Ð ÐÁÐÁThis annex only includes those elements of the Standard A INMARSAT system which have to be ЀÐimplemented for interworking purposes. ÐÐ Ð ÐÁÐÁInternal procedures such as those required for setting©up and clearing of the satellite link ЀÐare not shown. They are only indicated by task symbols. ÐÐ ÁÐÁOther procedures not shown are: ЀÐÁÐÁ©Á( Áinterruption control procedures related to the satellite link: ÐÐÁÐÁ©Á( Ápre©emption procedures for assigning channels to distress call. Ð ÐÁÐÁFor more details on the first generation INMARSAT Standard A signalling system, see Annex A. ÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÐ(€Ø ¨ðø%¸)x-ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌÐ Áà°MÁFIGURE B©1/Q.1101ƒ Áà°UÁƒ Áà°0Áà ÃState overview diagrams for incoming INMARSAT Standard A signalling systemÄ Äƒ Áà°MÁFIGURE B©2/Q.1101ƒ Áà°UÁƒ Áà°:Áà ÃNotes to incoming INMARSAT Standard A signalling systemÄ Äƒ Ð ÐÃÃÃÃwÄÄÄÄNote 1ÃÃwÄÄ © Includes also translation of prefixes to the appropriate destination number. Áà°MÁFIGURE B©3/Q.1101ƒ Áà°NÁ(sheet 1 of 2)ƒ Áà°UÁƒ Áà°>Áà ÃIncoming INMARSAT Standard A signalling systemÄ Äƒ ÃÃÃÃwÄÄÄÄNote 2ÃÃwÄÄ © Includes also address translated from any received prefixes. ÃÃÃÃwÄÄÄÄNote 3ÃÃwÄÄ © If implemented. Áà°MÁFIGURE B©3/Q.1101ƒ Áà°NÁ(sheet 2 of 2)ƒ Áà°UÁƒ Áà°>Áà ÃIncoming INMARSAT Standard A signalling systemÄ Äƒ Áà°RÁANNEX Cƒ Áà°UÁƒ Áà°HÁ(to Recommendation Q.1101)ƒ Áà°UÁƒ Áà°UÁƒ Áà°=Áà ÃLogic procedures for outgoing INMARSAT Standard AÄ Äƒ Áà°AÁà Ãsignalling system (shore originated call)Ä Äƒ Ð ÐÁÐÁThis annex only includes those elements of the INMARSAT Standard A system which have to be implemented for interworking purposes. Ð ÐÁÐÁInternal procedures such as those required for setting©up and clearing of the satellite link are not shown. They are only included by task symbols. ÁÐÁOther procedures not shown are: ÁÐÁ©Á( Áinterruption control procedures related to the satellite link; ÁÐÁ©Á( Ápre©emption procedures for assigning channels to distress calls. Ð ÐÁÐÁFor more details on the first generation INMARSAT Standard A signalling system, see Annex A. Áà°MÁFIGURE C©1/Q.1101ƒ Áà°UÁƒ Áà°1Áà ÃState overview diagram for outgoing INMARSAT Standard A signalling systemÄ Äƒ Áà°MÁFIGURE C©2/Q.1101ƒ Áà°UÁƒ Áà°HÁ(Reserved for future notes)ƒ Áà°MÁFIGURE C©3/Q.1101ƒ Áà°UÁƒ Áà°>Áà ÃOutgoing INMARSAT Standard A signalling systemÄ Äƒ ÁÐÁà ÃReferencesÄ Ä [1]ÁÐÁRadio Regulations (Article 1, No. 71), ITU, Geneva, 1982. [2]ÃÃÃÃwÄÄÄÄÁÐÁIbid.,ÃÃwÄÄ (Article 1, No. 73). Ð ð ÐÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿX8øè°"€%ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌÐÑ Âx„|ü@Ž ÑÃÃ)ÄÄ This is currently under study by INMARSAT.