Spirent Regulatory News (SPT)

1. Identity of the issuer or the underlying issuerof existing shares to which voting rights areattached: ii

SPIRENT COMMUNICATIONS PLC

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

Y

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

An event changing the breakdown of voting rights

Other (please specify):

3. Full name of person(s) subject to thenotification obligation: iii

FMR LLC

4. Full name of shareholder(s)  (if different from 3.):iv

See Section 9

5. Date of the transaction and date onwhich the threshold is crossed orreached: v

9th July 2014

6. Date on which issuer notified:

10th July 2014

7. Threshold(s) that is/are crossed orreached: vi, vii

5%

8. Notified details:

A: Voting rights attached to shares viii, ix

Class/type ofshares

if possible usingthe ISIN CODE

Situation previousto the triggeringtransaction

Resulting situation after the triggering transaction

NumberofShares

NumberofVotingRights

Numberof shares

Number of votingrights

% of voting rights x

Indirect

Direct xi

Indirect xii

Direct

Indirect

GB0004726096

30,530,400

30,530,400

30,998,000

30,998,000

5.06

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

Number of votingrights that may beacquired if theinstrument isexercised/ converted.

% of votingrights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

30,998,000

5.06

9. Chain of controlled undertakings through which the voting rights and/or thefinancial instruments are effectively held, if applicable: xxi

Proxy Voting:

10. Name of the proxy holder:

FMR LLC

11. Number of voting rights proxy holder will acquire:

467,600

12. Date on which proxy holder will acquire voting rights:

 9th July 2014

13. Additional information:

None

14. Contact name:

Shelley Muller

15. Contact telephone number:

fil-regreporting@fil.com, 01737 837216

C: Additional information

Contact at Issuer: Michelle Balch, Assistant Company Secretary, Spirent Communications plc

Telephone: 01293 767676