By Jack Fink

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DALLAS (CBS11) – Bridget Alex remains angry about her 6-month-old son Brandon’s death. “I want answers from T-Mobile. I want answers from 911. I want answers from the city.”

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On Saturday, she said her babysitter tried calling 911 on her T-Mobile cell phone three times from her North Dallas apartment, but no one picked up.

The City of Dallas said the babysitter hung up and that 911 operators returned each call, but couldn’t reach her.

“They didn’t call her back,” said Bridget Alex.

She said the babysitter, who’s a close friend, told her Brandon had fallen and was unresponsive.

At the time Alex said the babysitter was calling 911, the city said it received a surge in ghost 911 calls by T-Mobile numbers and that 422 people were placed on hold for about 30 to 40 minutes.

Alex said records from the babysitter’s cell phone show she first called 911 at 5:55 p.m. Saturday, but hung up after 51 seconds so she could perform CPR.

Alex said the babysitter called 911 at 5:57 p.m. and held on for eight minutes, 40 seconds – but no one picked up.

Then at 6:11 p.m., Alex said her babysitter called again and was on hold for 31 minutes.

“How can you say she hung up before you got to her? You had her on hold for 31 minutes, 31 minutes. When I came and picked up my son, she was still on hold with 911.”

Alex said she drove her son to the hospital herself.

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She said the babysitter told her police never went to the apartment after her three attempts to call 911.

But Alex said when she arrived at the hospital, Dallas police officers were there and spoke to her.

Little Brandon’s death comes as the City of Dallas and T-Mobile have tried to prevent the ghost calls for four months. “This has been going on since November 8. It takes for my son to die for him to be an example for you?”

CBS11 asked the City to respond to Ms, Alex’s claims, but the City didn’t do so Wednesday.

The City said Tuesday night that there is no evidence connecting the child’s death to the T-Mobile ghost call issue.

At a news conference late Wednesday afternoon with City of Dallas leaders and T-Mobile executives, Dallas Mayor Mike Rawlings said he called Ms. Alex and told her, “My heart is broken for the loss of a loved one and we’re going to get to the bottom of it.”

City and T-Mobile officials urged anyone who calls 911 and is placed on hold to stay on the line and not to hang up.

A CPS spokeswoman says the agency is investigating the baby’s death.

A CBS News team saw CPS investigators leave the South Dallas home where Ms. Alex is staying.

The CPS spokeswoman said there is no history with Ms. Alex.

Dallas police are also investigating.

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The Collin County Medical Examiner is trying to determine what caused the baby’s death.