European digital cellular telecommunications system (Phase 2) - Call Waiting (CW) and Call Hold (HOLD) supplementary services - Stage 2; English version ETS 300544:1995
Edition 1995-09

Integrated Services Digital Network (ISDN); Call Hold (HOLD) supplementary service; service description; english version ETS 300139:1992
Edition 1992-12

Integrated Services Digital Network (ISDN); Call Hold (HOLD) supplementary service; functional capabilities and information flows; english version ETS 300140:1992
Edition 1992-12

Integrated Services Digital Network (ISDN) - Call Hold (HOLD) supplementary service - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 1: Protocol specification
Edition 1998-09-01

Terrestrial Trunked Radio (TETRA) - Voice plus Data (V+D) - Part 11: Supplementary services stage 2 - Sub-part 12: Call Hold (HOLD)
Edition 2003-08-01

Terrestrial Trunked Radio (TETRA) - Voice plus Data (V+D) - Part 12: Supplementary services stage 3 - Sub-part 12: Call Hold (HOLD)
Edition 2003-08-01

Terrestrial Trunked Radio (TETRA) - Voice plus Data (V+D) - Part 10: Supplementary services stage 1 - Sub-part 12: Call Hold (HOLD)
Edition 2004-04-01

Integrated Services Digital Network (ISDN) - Call Hold (HOLD) supplementary service - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 2: Protocol Implementation Conformance Statement (PICS) proforma specification (incl. Diskette!!!)
Edition 1998-10-01

Digital cellular telecommunications system (Phase 2+) - Call Waiting (CW) and Call Hold (HOLD) supplementary services - Stage 3 (GSM 04.83 version 7.0.1 Release 1998)
Edition 2000-04-01

Integrated Services Digital Network (ISDN) - Call Hold (HOLD) supplementary service - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 5: Test Suite Structure and Test Purposes (TSS&TP) specification for the network
Edition 1998-09-01