September 11, 2008

Please Join Us for the F5 Networks Conference Call

F5 Networks (NASDAQ: FFIV):

 TOPIC:               F5 Fourth Quarter Financial Results  DATE:                Wednesday, October 22, 2008  TIME:                1:30 p.m. Pacific (4:30 p.m. Eastern)  DIAL IN NUMBER:      800-857-3834 (US & Canada) +1-210-839-8222 (International)  CALL LEADER:         John McAdam  PASSCODE:            F5 NETWORKS  Please call in 10 minutes ahead of time to ensure a proper connection. We look forward to having you join us. If you have any problems or questions, please call F5 NETWORKS, INC. (206) 272-5555.  REPLAY INFORMATION  Replay Via Phone:    Available October 22, 2008 (from 4:30 p.m. Pacific) through October 23, 2008 (until 5:00 p.m. Pacific)  Phone: 800-879-7966 (US & Canada) + 1-402-220-5346 (International)  Replay Via Internet: relations/events-calendar.html Available until January 21, 2009  Contact:             F5 Networks, Inc., Seattle John Eldridge, 206-272-6571 (Investor Relations) [email protected] 

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