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|                        What Is CELP ???                                     |
|                                                                             |
| CELP is a relatively new digital voice algorithm that permits high quality  |
|       digital voice communications over normal dial-up telephone lines.     |
|                                                                             |
| CELP was originally developed by AT&T Bell Laboratories Engineers working   |
|      with the National Security Agency (NSA). Today, CELP is covered by     |
|      a Federal Standard, Fed-Std-1016.                                      |
|                                                                             |
| CELP stands for "Code Excited Linear Prediction", the technical name        |
|     for the algorithm.                                                      |
|                                                                             |
| CELP digital voice in your STU-III will provide you with the best quality   |
|     digital voice communications available in any STU-III.                  |
|                                                                             |
| The AT&T STU-III with CELP capability is totally compatible with all other  |
|     STU-IIIs. If a non-CELP STU calls a CELP equiped STU, the secure link   |
|     will still be established using either the AT&T 4800 Voice or the       |
|     Interoperable 2400 Voice algorithm.                                     |
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