Automatic Secure Voice Communications Network

The Automatic Secure Voice Communications Network (AUTOSEVOCOM) was a worldwide, switched, secure voice network for the United States Armed Forces, which was operational from the late 1960s to the end of the 1980s. It was closely related to the Automatic Voice Network or AUTOVON, which was the main non-secure switched telephone network for the military.

Phase I

During the mid-1960s, the United States Government decided to implement a worldwide secure voice network. This was named Automatic Secure Voice Communications Network, or by its acronym AUTOSEVOCOM, and was the National Security Agency's first program for the United States Department of Defense's telephone protection. It was a cumbersome and expensive system that was available only for high-level users. Because of its inadequacies, the Defense Department capped it at 1850 terminals, and in the late 1960s, hoping for something better, decided not to continue with the expansion of AUTOSEVOCOM.^[1]

Phase I of the network was approved by the Deputy Secretary of Defense in July 1967 and after that it took several years to implement AUTOSEVOCOM within the continental United States. AUTOSEVOCOM-I was a non-tactical network that enabled users to discuss classified or sensitive information over the telephone. The network consisted of switching centres, transmission facilities and subscriber terminals. Subscribers were homed either on an AUTOSEVOCOM switch, on an Automatic Voice Network (AUTOVON) switch, or a Joint Overseas Switchboard (JOSS), which were for example operated and maintained by numerous Signal Battalions in Vietnam.

The AUTOSEVOCOM switches provided for wideband secure voice communications between local subscribers and enabled them to establish long-distance secure voice calls. The majority of the long-distance calls were routed by the AUTOVON.

Phase II

Difficulties with speech intelligibility, requirements for voice recognition,^[2] the holding of telephone conferences, speedier service, and simpler calling procedures led Defense officials to approve the development of an improved system, called AUTOSEVOCOM II. The Army was designated as the agency with the primary responsibility of developing the system. In May 1976, the Deputy Secretary of Defense approved the full-scale development of the AUTOSEVOCOM II programme.

AUTOSEVOCOM II incorporated technological advances and furnished higher quality communications for the several thousand subscribers who were expected to use it when put into operation during the years 1980 to 1985. The U.S. Army Communications Command acted as program manager for AUTOSEVOCOM II.

The Automatic Secure Voice Communications Network was succeeded by the Defense Red Switch Network (DRSN) and the STU-III secure phones. The last AUTOSEVOCOM secure voice switch in the world was deactivated at the Pentagon in 1994.^[3]

External links

References

^ Thomas R. Johnson, American Cryptology during the Cold War, 1945-1989, 1998, Chapter 17, p. 142.
^ How to Wreck a Nice Beach: The Vocoder from World War II to Hip-Hop, By Dave Tompkins
^ Christopher H. Sterling, Military Communications: From Ancient Times to the 21st Century, 2008, p. 48-49.

[1] Thomas R. Johnson, American Cryptology during the Cold War, 1945-1989, 1998, Chapter 17, p. 142.

[2] How to Wreck a Nice Beach: The Vocoder from World War II to Hip-Hop, By Dave Tompkins

[3] Christopher H. Sterling, Military Communications: From Ancient Times to the 21st Century, 2008, p. 48-49.

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v t e United States Air Force system numbers
100–199	100 101 P 102 103 104 105 106¹ 107 A-1 A-2 108¹ 109¹ 110 111¹ 112 113¹ 114¹ 115¹ 116¹ 117 L M 118 A L P 119 C/F E L T Y 120 121 122 123 124 125 126 127¹ 128 129 130 131 132 A B 133 134¹ 135 136¹ 137¹ 138 139 140 141¹ 142 143–197¹ 198 199 B C D Y
200–299	200 201 A/L B/W E 202 203¹ 204 205 206 207¹ 208 209¹ 210 211¹ 212 213 214 215¹ 216 217 218 219¹ 220 221 222 A G 223¹ 224 225¹ 226 227–238¹ 239 240–278¹ 279 280–298¹ 299
300–399	300 301¹ 302 303 304¹ 305¹ 306 A/L B 307 308 309 310¹ 311¹ 312¹ 313¹ 314 315 A-1 A-2 316 317 318¹ 319 320¹ 321 322¹ 323 324 L M/N 325 326 327 E 328 E 329 F 330¹ 331¹ 332¹ 333¹ 334¹ 335 336 337 338–379¹ 380 A/B/E/F/N P 381–397¹ 398 399 A B
400–499	400 B/C/N E G/H M 401 402 403¹ 404 405 B C D 406¹ 407 408¹ 409¹ 410 E L 411 E L 412 413 414 L M 415 416 L M (I) M (II) P Q 417 418 L M 419¹ 420 L/W 421¹ 422 423 424 425 426 L M 427 L M 428 A L 429 430 431 G (I) G (II) 432 433 434 435 A L 436 437 438 439 440 441 A D L 442 443 444¹ 445 L M 446 447 448¹ 449¹ 450 451 D L 452 453 454¹ 455 456 457¹ 458 459 460 L 461 462 463 464 465 466 467 468 469 470 471 L (I) L (II) 472 473 474 L N 475¹ 476 E 477 478 A T 479¹ 480 481 L 482 E L M/Z 483 484 L M N 485 L Z 486 487 488 489 490 L M 491¹ 492 493 494 495 L (I) L (II) 496 497 A L (I) L 498 A C D E L 499 A C D
500–599	500 501–519¹ 520 521–529¹ 530 531–541¹ 542 543–549¹ 550 A E 551–559¹ 560 A F 561–569¹ 570 571–579¹ 580 A E 581–589¹ 590 591 592 593–599¹
600–699	600 601 A L 602 A L 603 A L 604 605 606 607 608¹ 609 610¹ 611¹ 612¹ 613¹ 614 615¹ 616 617¹ 618 619¹ 620 621 A/B (I) B (II) 622 623 624 625 626¹ 627 628¹ 629¹ 630¹ 631¹ 632 633 634 A B 635 636¹ 637¹ 638 639 640 641 642 643 644¹ 645¹ 646¹ 647¹ 648 A D P 649 A B C D E F L P 650 651 652 653¹ 654¹ 655 A (I) A (II) P 656 657¹ 658¹ 659¹ 660 661 662¹ 663¹ 664 665 A (I) A (II) 666 A C/P 667 668 669¹ 670 671¹ 672 A M/P 673¹ 674 675 676¹ 677¹ 678¹ 679 680 681 D E 682¹ 683 A J V 684¹ 685 686 687 J P 688¹ 689¹ 690 691 C X Z 692¹ 693 694¹ 695 A B C L N P Q R S (I) S (II) 696¹ 697¹ 698¹ 699¹
700–799	700–735¹ 736 737¹ 738¹ 739¹ 740¹ 741 742 743 744¹ 745 746–753¹ 754 755–799¹
800–899	800¹ 801¹ 802 L (I) L (II) 803¹ 804¹ 805¹ 806 807 808–816¹ 817 818¹ 819¹ 820¹ 821¹ 822¹ 823 824–831¹ 832 833¹ 834 835–845¹ 846 847–899¹
900–999	900–951¹ 952 853¹ 854¹ 855¹ 956 957–967¹ 968
¹ Unknown or not assigned