IPhone 4S Siri Will No Longer Voice Dial Contacts - Always Call Failed

Question

I am not exactly sure when this started (5.0.1?), but when I ask Siri to dial someone in my contacts, Siri recognizes the request, proceeds to Dial the number and no matter which contact I try, I get an immediate "CALL FAILED" and then the iPhone immediately locks. I have restored the iPhone as new, Reset Network Settings, etc. to no avail. If I turn Siri off from Settings, the phone will revert to the previous Voice Control that was present in previous iPhones and Voice Calls are successful. Only when trying to use Siri do all voice initiated calls fail. And it is 100% consistent in the failure. This does not appear to be a Siri network issue, as all Siri other Siri requests work and are speedy. Co-workers with the 4S are also experiencing the same issue, so it does not appear to be specific to just my iPhone. Can anyone else confirm? Thanks.

Answer 1

OK, so i have tracked it down to a single AT&T Cell Tower location in my instance, but it also just so happens to be at my office, which means I am affected by it all day. What is happening is that at this particular location, the AT&T tower is misconfigured or experiencing some type of technical issue, resulting in the inability of the cell tower to handle simultaneous voice and data. Siri uses data to match the contacts, names etc and hands off to the Phone dialer, which immediately experiences a call failure as a result of the 3G Data still being in use by Siri. You can verify simultaneous voice and data connectivity by placing a voice call and then attempting to use 3G data (you must not be using WiFi to determine if this is a problem with the Cell network). While in a voice call, launch the Speedtest.net Mobile Speed Test app. You will clearly see that 3G data services have all but ceased if this is your problem. End the Voice Call and run the Speedtest.net Mobile Speed Test again and 3G data will work fine.
I have reported the problem via AT&T's Mark the Spot App numerous times and had my colleagues do the same and called AT&T Wireless customer service to no avail. They simply refuse to acknowledge the issue is on their end. I personally know at least 5 other iPhone 4S users in my office who are experiencing the same issue and the results can be consistently recreated on all of their devices. And again, once they leave the office in the afternoon, all of their services return to normal and they can again make and place Voice initiated phone calls without the dreaded Call Failed. Thanks AT&T.