Holding(s) in Company

Spirent Communications PLC
21 July 2006

                   NOTIFICATION OF MAJOR INTERESTS IN SHARES


1. Name of listed company

SPIRENT COMMUNICATIONS PLC

2. Name of shareholder with a major interest

SUN LIFE ASSURANCE COMPANY OF CANADA (UK) LIMITED

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

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

ROY Nominees                                                         21,832,301
ROY Nominees                                                          2,429,640
                                                                   ____________
TOTAL                                                                24,261,941


5. Number of shares / amount of stock acquired

-

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

-

7. Number of shares / amount of stock disposed

NOT KNOWN

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

NOT KNOWN

9. Class of security

ORDINARY SHARES OF 3.3333 PENCE EACH

10. Date of transaction

NOT NOTIFIED

11. Date company informed

20 JULY 2006

12. Total holding following this notification

24,261,941

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)

2.58%

14. Any additional information

SHAREHOLDER NO LONGER HAS A REPORTABLE HOLDING IN THE COMPANY.  SHAREHOLDER 
PREVIOUSLY REPORTED THAT IT HAD A HOLDING OF 29,765,267 SHARES (3.08%) IN THE 
COMPANY ON 20 JANUARY 2006

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

21 JULY 2006



                      This information is provided by RNS
            The company news service from the London Stock Exchange