Crawley, UK -- (MARKET WIRE) -- October 31, 2006 --

Spirent Communications Plc

Transaction in Own Shares

Spirent Communications PLC announces that it has today purchased through Citigroup Global Markets U.K. Equity Limited 1,000,000 ordinary shares at an average price of 56.9433 pence per share. The highest price and the lowest price paid for these shares were 57.75 pence and 56.75 pence respectively.

Following the above purchase, Spirent Communications plc holds 83,790,000 Spirent Communications plc ordinary shares in treasury, and has 890,635,005 Spirent Communications plc ordinary shares in issue (excluding treasury shares).

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