Cisco Systems was a company that created many of the technologies used by CTU Los Angeles and CTU New York as well as the White House.
Day 4[]

The Cisco Security Response System
The CTU Los Angeles computer network had Cisco Security Response System software installed on it sometime in the week before Day 4. When Yassir attempted to disable their satellite system with a denial of service attack, Chloe O'Brian noticed large spikes of network activity, and the security system blocked the attack.
Day 6[]

Yuri Suvarov appears on the Cisco teleconference suite.
Vice President Noah Daniels and his staff communicated with Yuri Suvarov and the Russian staff using the Cisco TelePresence suite.
Day 8[]
Cisco's 'Telepresence' video conferencing software was used and it's video surveillance manager was extensively used particularly during the manhunt of Jack Bauer at the First Unity Savings Bank on Lexington, where Cisco's Video Surveillance Manager was used to run facial recognition through a series of IP cameras located on the interior and the exterior of the bank building. ("Day 8: 11:00am-12:00pm")
The United Nations building also used Cisco IP phones and were prominently seen in most conference & private rooms in the building.
Background information and notes[]

A Cisco IP phone in Season 1
- Cisco Systems was a corporate sponsor of the show, credited for providing promotional sponsorship for "Day 4: 4:00am-5:00am", "Day 4: 5:00am-6:00am", "Day 4: 6:00am-7:00am", "Day 5: 5:00am-6:00am", "Day 6: 1:00am-2:00am" and "Day 6: 3:00am-4:00am".
- 24 featured a number of different technologies belonging to Cisco during 24, including their IP phones, firewall technology, and videoconferencing facilities.