EXHIBIT 4.24

                  AMENDMENT NUMBER SIX TO AMENDED AND RESTATED
                           LOAN AND SECURITY AGREEMENT

      This  Amendment  Number  Six to Amended  and  Restated  Loan and  Security
Agreement  ("Amendment")  is  entered  into as of August 1, 1998 by and  between
FOOTHILL CAPITAL CORPORATION,  a California corporation ("Foothill"),  and PORTA
SYSTEMS CORP., a Delaware corporation ("Borrower"), in light of the following:

      FACT ONE: Borrower and Foothill have previously  entered into that certain
Amended and Restated Loan and Security Agreement, dated as of November 28, 1994,
as amended as of February 13, 1995, March 30, 1995,  March 12, 1996,  August 26,
1997 and November 30, 1997 (collectively, the "Agreement").

      FACT TWO:  Borrower and Foothill  desire to further amend the Agreement as
provided for and on the conditions herein.

      NOW,  THEREFORE,  Borrower  and  Foothill  hereby  amend the  Agreement as
follows:

      1.  DEFINITIONS.  All initially  capitalized  terms used in this Amendment
shall  have the  meanings  given to them in the  Agreement  unless  specifically
defined herein.

      2. AMENDMENT.

      2.1.  Renewal and  Extension of Term of  Agreement.  Borrower and Foothill
desire to renew the term of the Agreement and extend the expiration  date of the
term of the Agreement to January 2, 2000. The Agreement is amended as follows to
reflect such renewal and extension:

            A.  The  definition  of the  "Renewal  Date" in  Section  1.1 of the
      Agreement is hereby  amended by deleting  such  definition in its entirety
      and replacing it with the following definition:

                  "'Renewal Date' means January 2, 2000."

            B. Section 3.4 of the  Agreement is hereby  amended by deleting such
      Section in its entirety and replacing it with the following language:

                  "3.4 Term.  This  Agreement  shall become  effective  upon the
            execution  and  delivery  hereof by Borrower  and Foothill and shall
            continue in full force and effect for a term ending January 2, 2000,
            and the maturity date of the Term Note, the Deferred Funding Fee

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            Note and the NWE  Deferred  Fee Note  shall also be January 2, 2000.
            The  foregoing  notwithstanding,  Foothill  shall  have the right to
            terminate  its  obligations  under this  Agreement  immediately  and
            without notice upon the occurrence and during the continuation of an
            Event of Default."

      2.2 LOAN  AMORTIZATION.  Effective  as of August 1,  1998,  all  principal
payments  made by Borrower to Foothill  pursuant to Section 2.9 of the Agreement
shall be applied first to the NEW Deferred  Funding Fee Note until it is paid in
full, second to the Deferred Funding Fee Note until it is paid in full and third
to the Term Note. As of July 31, 1998, the outstanding  principal balance of the
NEW Deferred Funding Fee Note was $300,000 and the outstanding principal balance
of the Deferred Funding Fee Note was $2,784,394.73.

      3.  REPRESENTATIONS  AND  WARRANTIES.  Borrower hereby affirms to Foothill
that all of Borrower's  representation and warranties set forth in the Agreement
are true, complete and accurate in all respects as of the date hereof.

      4. NO  DEFAULTS.  Borrower  hereby  affirms to  Foothill  that no Event of
Default has occurred and is continuing as of the date hereof.

      5. CONDITION  PRECEDENT.  The effectiveness of this Amendment is expressly
conditioned upon receipt by Foothill of an executed copy of this Amendment.

      6. COSTS AND  EXPENSES.  Borrower  shall pay to Foothill all of Foothill's
out-of-pocket costs and expenses  (including,  without limitation,  the fees and
expenses of its  counsel,  which  counsel may include any local  counsel  deemed
necessary, search fees, filing and recording fees, documentation fees, appraisal
fees,  travel  expenses,   and  other  fees)  arising  in  connection  with  the
preparation,   execution,  and  delivery  of  this  Amendment  and  all  related
documents.

      7.  LIMITED  EFFECT.  In the  event of a  conflict  between  the terms and
provisions of this Amendment and the terms and provisions of the Agreement,  the
terms and provisions of this Amendment shall govern. In all other respects,  the
Agreement,  as amended and supplemented  hereby,  shall remain in full force and
effect.

      8.  COUNTERPARTS;  EFFECTIVENESS.  This  Amendment  may be executed in any
number of counterparts and by different parties on separate  counterparts,  each
of which when executed and delivered shall be deemed to be an original. All such


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counterparts,  taken together, shall constitute one and the same Amendment. This
Amendment  shall become  effective  upon the  execution of a conterpart  of this
Amendment by each of the parties hereto.

      IN WITNESS WHEREOF,  the parties hereto have executed this Amendment as of
the date first set forth above.

                                            FOOTHILL CAPITAL CORPORATION,
                                            a California corporation

                                            By: /s/ M.E. Stearns
                                               ---------------------------------
                                            Title: VP
 

                                            PORTA SYSTEMS CORP.,
                                            a Delaware corporation    
                                                      
                                            By: /s/ Edward B. Kornfeld
                                               ---------------------------------
                                            Title: Sr. V.P. Operations  
 

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      Each of the  undersigned  affiliates of Porta  Systems Corp.  ("Porta") is
aware of the terms of the above Amendment Number Six to the Amended and Restated
Loan and Security Agreement,  dated as of August 1, 1998 (the "Loan Agreement"),
and  acknowledges  that all of such  affiliate's  obligations  under  any of the
Collateral  Documents  (as defined in the  Assignment  Agreement)  are and shall
continue  in full  force and  effect in favor of  Foothill  Capital  Corporation
("Foothill"),  including the  obligations to guarantee the  obligations of Porta
owing to Foothill and to secure such  obligations  pursuant to the terms of such
Collateral Documents.  "Assignment Agreement" shall have the meaning given to it
on the Loan Agreement.

                                              ASTER CORPORATION  
                                              
                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name: Michael A. Tancredi
                                              Title: Sr. Vice President
                                                     Secretary and Treasurer
                                              
                                             
                                              CPI HOLDING CORP.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                             
                                              CRITERION PLASTICS, INC.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                              
                                              DISPLEX, INC.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:


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                                              MIROR TELEPHONY SOFTWARE, INC.
                                              
                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                              
                                              PORTA FOREIGN SALES CORP.
                                              
                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                              
                                              PORTA SYSTEMS EXPORT CORP.
                                              
                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                             
                                              
                                              PORTA SYSTEMS INTERNATIONAL CORP.
                                              
                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                             
                                              
                                              PORTA SYSTEMS LEASING CORP.
                                              
                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:


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                                              PORTA SYSTEMS OVERSEAS CORP.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                              
                                              LERO INDUSTRIES LTD.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                              
                                              PORTA SYSTEMS, LIMITED

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                              
                                             
                                              VANDERHOFF BUSINESS SYSTEMS LTD.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:
                                             
                                              
                                              VANDERHOFF COMMUNICATIONS LTD.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title:


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                                              PORTA SYSTEMS S.A. de C.V.

                                              By: /s/ Michael A. Tancredi
                                                 -------------------------------
                                              Name:
                                              Title: