Oakland police officers began experiencing sporadic problems July 25, the day Obama was in Oakland speaking to an overflowing crowd at the Fox Theatre. Outside, protesters roamed the streets.
One hundred officers were assigned to handle problems that could arise. Many said they had problems communicating on their two-way radios.
Police Chief Howard Jordan told reporters the next day the cause of the problem was a cooling system that broke down, causing one of three radio towers to fail. But officers have been complaining that the new radio system, which was installed only a year ago, has been riddled with interference and glitches right from the start.
An internal city investigation found the cause four days ago -- AT&T's cell sites in Oakland were interfering with the city's radio system.
"We're in the 850 megahertz band, just very close to where AT&T is and their system is just bleeding over into our sites," Oakland Public Safety Systems Advisor David Cruise told ABC7 News.
The FCC was called in and they verified the findings.
The city says AT&T has now stopped services at 16 of its cell sites in Oakland that have affected radio system.
"There are so many cell phone towers and they're everywhere," Mayor Jean Quan said. "I don't know about you, but I'm finding more and more, even on my cellphone, I'm having a harder time finding places where I can talk to people without interference and interruption and the same thing is apparently happening with these."
AT&T says it has not shut down any of its cell sites, that it's only "temporarily suspended operating its 2G network on a limited number of sites" and that they are operating its 2G network on other cell sites with minimal impact on customers. They also say their 3G and 4G networks have not been affected.
Oakland looking into whether other nearby cities are experiencing similar incidents.