Holding(s) in Company

Spirent Communications PLC
24 July 2006


                   NOTIFICATION OF MAJOR INTERESTS IN SHARES



1. Name of listed company

SPIRENT COMMUNICATIONS PLC


2. Name of shareholder with a major interest

PRUDENTIAL PLC


3. Please state whether notification indicates that regarding the holding of the
shareholder named in 2 above; in respect of a non-beneficial interest; or in the
case of an individual holder if it is a holding of that person's spouse or
children under the age of 18

SHAREHOLDER IN 2 ABOVE AND CERTAIN OF ITS SUBSIDIARY COMPANIES


4. Name of the registered holder(s) and, if more than one holder, the number of
shares held by each of them

JP MORGAN NOMINEES                                              568,490
MAGIM HSBC GIS NOM (UK) SALI                                    566,983
PRUCLT HSBC GIS NOM (UK) PAC AC                              28,473,727
PRUCLT HSBC GIS NOM (UK) PPL AC                               6,095,990
PRUCLT HSBC GIS NOM (UK) EQBF AC                                270,027
PRUCLT HSBC GIS NOM (UK) MNBF AC                                440,603
PRUCLT HSBC GIS NOM (UK) PENE AC                              1,702,386
TOTAL                                                        38,118,206



5. Number of shares / amount of stock acquired

NOT KNOWN


6. Percentage of issued class (any treasury shares held by the listed company
should not be taken into account when calculating percentage)

NOT KNOWN


7. Number of shares / amount of stock disposed

-


8. Percentage of issued class (any treasury shares held by the listed company
should not be taken into account when calculating percentage)

-


9. Class of security

ORDINARY SHARES OF 3.3333 PENCE EACH


10. Date of transaction

NOT NOTIFIED


11. Date company informed

21 JULY 2006


12. Total holding following this notification

38,118,206


13. Total percentage holding of issued class following this notification (any
treasury shares held by the listed company should not be taken into account when
calculating percentage)

4.06%


14. Any additional information

ON 15 DECEMBER 2005 THE SHAREHOLDER REPORTED TO THE COMPANY THAT IT HAD
INCREASED ITS HOLDING IN THE COMPANY TO 32,880,110 SHARES (3.4%)


15. Name of contact and telephone number for queries

MICHAEL ANSCOMBE - 01293 767672


16. Name and signature of duly authorised company official of the listed company
responsible for making this notification

MICHAEL ANSCOMBE - DEPUTY COMPANY SECRETARY


Date of notification

24 JULY 2006



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