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                                  EXHIBIT 5.1

                                  May 20, 1998


Aspect Telecommunications Corporation
1730 Fox Drive
San Jose, CA  95131-2312

        REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

        We have examined the Registration Statement on Form S-8 to be filed by
you with the Securities and Exchange Commission on or about May 20, 1998 (the
"Registration Statement") in connection with the registration under the
Securities Act of 1933, as amended effective, of a total of 441,832 shares of
your Common Stock (the "Shares") reserved for issuance under the Company's
assumed Voicetek Corporation 1992 Equity Incentive Plan and the Voicetek
Corporation 1996 Stock Option Plan (the "Option Plans"). As your legal counsel,
we have examined the proceedings taken and are familiar with the proceedings
proposed to be taken by you in connection with the sale and issuance of the
Shares under the Option Plans.

        It is our opinion that, when issued and sold in the manner referred to
in the Option Plans and pursuant to the respective agreement which accompanies
each grant under the Option Plans, the Shares will be legally and validly
issued, fully paid and nonassessable.

        We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever it appears in the
Registration Statement and any amendments to it.

                                              Sincerely,                   


                                              
                                              VENTURE LAW GROUP
                                              A Professional Corporation

                                              /s/ VENTURE LAW GROUP