Who is to blame for the death of 6-month-old Brandon Alex?

His mother, Bridget Alex wants answers.

"There’s no excuse you can give me to make sure this pain go away. I just want them to own up to their responsibility because somebody did something wrong and my son is not here anymore,” Alex told WFAA.

Alex says her babysitter couldn’t get through to 911 on Saturday night and was placed on hold. It’s a problem WFAA first reported on February 8, but the problem hasn’t been fixed.

”If your 911 system breaks people do die,” said Councilman Philip Kingston.

Initially the City and DPD said the problem was with T-Mobile.

When a caller dialed 911, their phone would inadvertently ghost dial multiple times, jamming the system. So people calling 911 were placed on hold sometimes for more than 30 minutes at a time.

But Thursday, the City said T-Mobile now says the problem is a result of callers abandoning calls and hanging up before an operator answers.

City Councilman Philip Kingston isn’t buying it.

"How could there suddenly be so many T-Mobile callers calling 911 and dropping off before calls are answered. On its face looks like balogna.”

The City also says the backlog is complicated by the fact that their equipment is old and outdated.

Attorney Emmanuel Obi has been pushing the City to upgrade for years.

”The equipment was created in another era and it’s having issues competing with new modern aspects of technology,” Obi told WFAA.

The City of Dallas gets millions of dollars every year from cell phone user fees. The money that should go towards upgrading and maintaining 911's emergency service.

So where is the money?

"This is one of the reasons we wanted to bring a new city manager, is we need culture change at City Hall with transparency and accountability... so where is the money and where has it gone?” asked Dallas City Councilman Scott Griggs.

T-Mobile after months of conference calls with DPD finally dispatched engineers to Dallas and they have made some changes they hope will help fix the problem.

Only time will tell if the changes work.

WFAA has learned that there is also a staffing shortage in the 911 call center. On some nights for the entire city of Dallas they have only four or five operators working, and that complicates the matter further.

The City is bringing in Dallas police officers on overtime to help answer calls.