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� Home : ITU-T : Publications : Recommendations : Q�Series : Q.21 : Q.21 (11/88)
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Q.21�:�Systems recommended for out-band signalling �

Recommendation Q.21 (11/88)

Approved in 1988-11-25

Status : In force

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PDF Document PDF (acrobat)

50211 bytes 1990-05-29 E�15166�
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PDF Document PDF (acrobat)

55654 bytes 1990-05-29 S�15166�
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PDF Document PDF (acrobat)

56083 bytes 1990-05-29 F�15166�

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Format Size Posted Article Number TIES users
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Word Document Word

33471 bytes 1990-05-29 E�15166� Download
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Word Document Word

43592 bytes 1990-05-29 S�15166� Download
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Word Document Word

42293 bytes 1990-05-29 F�15166� Download

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