December 13, 1999


Westell Technologies, Inc.
750 North Commons Drive

Aurora, IL

Gentlemen:

                  Reference is made to the 6% Subordinated Convertible Debenture
("Debenture")  dated April 15, 1999 in the principal amount of $5,000,000 issued
by Westell  Technologies,  Inc.  ("Company ") to Capital Ventures  International
("Investor")  and the Stock Purchase Warrant  ("Warrant")  issued to Investor by
the Company dated April 15, 1999 for the right to purchase 227,273 shares of the
Company Class A common stock.

                  This  Letter  Agreement  documents  the  following  agreements
between Investor and the Company:

         1. In  consideration  of the issuance  described in Paragraph 2 of this
Letter Agreement,  Investor agrees that as to any transaction first announced by
December 31, 1999, the phrase  "except for issuances  which do not exceed 20% of
the Class A Common Stock " in the first  sentence of Section 4(e) of the Warrant
and the first  sentence of Section 8.3 of the Debenture  shall be deemed to read
"except for issuances to shareholders of the other party which do not exceed 41%
(calculated on an after issuance basis) of the outstanding  common stock of both
classes of the Company."

         2. The  Warrant  is hereby  amended to reduce  the  Exercise  Price (as
defined in the Warrant) from $8.9208 to $5.9208,  subject to further  adjustment
from time to time in accordance with the Warrant. The number of shares of Common
Stock  issuable  upon exercise of the Warrant shall not be adjusted by reason of
the reduction in Exercise Price effected by this Paragraph 2; and there shall be
no further Exercise Price adjustment  pursuant to Section 4(a) of the Warrant on
account of a Company  Transaction which is subject to the waiver of Paragraph 1.
There shall be no adjustment to the Conversion  Price of the Debenture by virtue
of the Warrant Exercise Price adjustment herein.

         3. The  Investor  hereby  releases  and waives any claims  against  the
Company  for  money  payments,  damages,  Warrant  Exercise  Price  adjustments,
Debenture  Conversion Price  adjustments or otherwise which arise or could arise
or be assertable by reason of any action or occurrence under Section 8.10 of the
Debenture or Section 4(l) of the Warrant from April 15, 1999 through the date of
this Letter Agreement.





         4. It is  acknowledged  that the " six month  period" in the proviso of
the penultimate sentence of Section 8.10 of the Debenture and the proviso in the
last sentence of Section 4(l) of the Warrant is the period  beginning  April 15,
1999 and ending February 28, 2000.

         5. Each party  represents  and warrants to the other that the execution
of this Letter Agreement by it has been authorized by all necessary  corporation
action,  including,  for the  Company,  by its Board of  Directors.  This Letter
Agreement  shall  constitute  an amendment to both the Debenture and the Warrant
and shall bind successor  holders to the Debenture and the Warrant.  The Company
shall not be required  to register  any  transfer  of the  Debenture  or Warrant
unless the  transferee  acknowledges  the  amendment  thereto  under this Letter
Agreement.

         6. The undersigned  acknowledges  that the Company may be entering into
agreements with the other holders of warrants and debentures issued on April 15,
1999 which address the matters covered by this Letter Agreement.  There shall be
no adjustment to the Warrant Exercise Price or the Debenture Conversion Price on
account of execution of any such agreements.


                                        Capital Ventures International
                                        By Heights Capital Management, as agent


                                        By /s/Andrew Frost, president

Westell Technologies, Inc.

By/s/ Marc Zionts, executive vice president
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