<PAGE>

                                                                      EXHIBIT 12

                       WILLIAMS COMMUNICATIONS GROUP, INC.

               COMPUTATIONS OF RATIO OF EARNINGS TO FIXED CHARGES
               AND RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND
                      PREFERRED STOCK DIVIDEND REQUIREMENTS

<Table>
<Caption>

                                                                 THREE MONTHS ENDED
                                                                      MARCH 31,
                                                          ------------------------------
                                                              2002             2001
                                                          ------------      ------------
                                                                  (IN THOUSANDS)
<S>                                                          <C>                <C>
Earnings:
   Loss before income taxes                               $   (283,360)     $   (259,104)
   Add:
     Interest expense -- net                                   131,086            82,483
     Rental expense representative of interest factor           24,333            30,895
     Minority interest in loss of consolidated
        subsidiary                                              (4,684)           (6,608)
     Equity losses                                               1,169             5,901
                                                          ------------      ------------
        Total loss as adjusted plus fixed charges
                                                          $   (131,456)     $   (146,433)
                                                          ============      ============
Fixed charges and combined fixed charges and
   preferred stock dividend requirements:
     Interest expense -- net                              $    131,086      $     82,483
     Capitalized interest                                        2,498            34,019
     Rental expense representative of interest factor           24,333            30,895
                                                          ------------      ------------
        Total fixed charges                                    157,917           147,397

     Preferred stock dividends and amortization of
         preferred stock issuance costs                          4,398             4,416
                                                          ------------      ------------
     Combined fixed charges and preferred stock
         dividend requirements                            $    162,315      $    151,813
                                                          ============      ============

Ratio of earnings to fixed charges                                 (a)               (a)
                                                          ============      ============

Ratio of earnings to combined fixed charges and
   preferred stock dividend requirements                           (b)               (b)
                                                          ============      ============
</Table>

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(a)    Earnings were inadequate to cover fixed charges by $289,373,000 and
       $293,830,000 for the three months ended March 31, 2002 and 2001,
       respectively.

(b)    Earnings were inadequate to cover combined fixed charges and preferred
       stock dividend requirements by $293,771,000 and $298,246,000 for the
       three months ended March 31, 2002 and 2001, respectively.