Page 17 of 20 pages



                                    EXHIBIT B

POWER OF ATTORNEY

     The undersigned hereby make, constitute and appoint each of EDWARD F.
GLASSMEYER and ANN H. LAMONT, acting jointly or individually, with full power
of substitution, the true and lawful attorney-in-fact for the undersigned, in
the undersigned's name, place and stead and on the undersigned's behalf, to
complete, execute and file with the United States Securities and Exchange
Commission (the "Commission"), a statement on Schedule 13G with respect to
the securities of any or all of the following entities:

     AIRSPAN NETWORKS INC., a Washington corporation;
     AVENUE A, INC., a Washington corporation;
     AVICI SYSTEMS INC., a Delaware corporation;
     CLICKSOFTWARE TECHNOLOGIES, LTD., an Israel corporation;
     DSL.NET, INC., a Delaware corporation;
     ESPERION THERAPEUTICS, INC., a Delaware corporation;
     INTERNAP NETWORK SERVICES CORPORATION, a Washington corporation;
     METAWAVE COMMUNICATIONS CORPORATION, a Delaware corporation;
     MOBIUS MANAGEMENT SYSTEMS, INC., a Delaware corporation;
     ORAPHARMA, INC., a Delaware Corporation;
     PIVOTAL CORPORATION, a British Columbia corporation;
     PRIMUS KNOWLEDGE SOLUTIONS, INC., a Washington corporation;
     QUINTUS CORPORATION, a Delaware corporation;
     REPEATER TECHNOLOGIES, INC., a Delaware corporation;
     TRITON NETWORK SYSTEMS, INC., a Delaware corporation;
     VICINITY CORPORATION, a Delaware corporation;
     VIRATA CORPORATION, a Delaware corporation; and
     WIRELESS FACILITIES, INC., a Delaware corporation;

and any and all amendments thereto pursuant to Section 13(d) of the Securities
Exchange Act of 1934, as amended, and the rules and regulations promulgated
thereunder, and any other forms, certificates, documents or instruments
(including a Joint Filing Agreement) that the attorneys-in-fact (or either of
them) deems necessary or appropriate in order to enable the undersigned to
comply with the requirements of said Section 13(d) and said rules and
regulations.

     This Power of Attorney shall remain in effect for a period of two years
from the date hereof or until such earlier date as a written revocation thereof
is filed with the Commission.

Dated: February 14, 2001



                                                            Page 18 of 20 pages
     Oak Management Corporation

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  President



     Oak Investment Partners VI, Limited Partnership
     By: Oak Associates VI, LLC, its general partner

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak Associates VI, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak VI Affiliates Fund, Limited Partnership
     By:  Oak VI Affiliates, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak VI Affiliates, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak Investment Partners VII, Limited Partnership
     By:  Oak Associates VII, LLC, its general partner

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member




                                                            Page 19 of 20 pages
     Oak Associates VII, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak VII Affiliates Fund, Limited Partnership
     By:  Oak VII Affiliates, LLC, its general partner

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak VII Affiliates, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak Investment Partners VIII, Limited Partnership
     By:  Oak Associates VIII, LLC, its general partner

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak Associates VIII, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     Oak VIII Affiliates Fund, Limited Partnership
     By:  Oak VIII Affiliates, LLC, its general partner

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



                                                            Page 20 of 20 pages

     Oak VIII Affiliates, LLC

     By: /s/ Edward F. Glassmeyer
         -----------------------------------------
     Name:  Edward F. Glassmeyer
     Title:  Managing Member



     /s/ Bandel L. Carano
     ---------------------------------------------
     Bandel L. Carano



     /s/ Gerald R. Gallagher
     ---------------------------------------------
     Gerald R. Gallagher



     /s/ Edward F. Glassmeyer
     ---------------------------------------------
     Edward F. Glassmeyer



     /s/ Fredric W. Harman
     ---------------------------------------------
     Fredric W. Harman



     /s/ Ann H. Lamont
     ---------------------------------------------
     Ann H. Lamont