Received automated phone call saying my account had been suspended until I verify it.

I have a post-paid wireless account. I have one phone number and device on the account. I received an automated call this morning at around 0750 that said that my wireless account had been suspended and that the purpose of the call was to verify the account. The machine then asked for the last 4 digits of my SSN. I noted the phone number and hung up on the call. When I called the phone number back, another computer eventually told me that I had to wait until a person came to work at 0800 to answer my question.The phone and number belong to my spouse. I just called her to confirm whether the phone was in service. She answered it and I told her what happened.

Whoever at AT&T decided to do this process has his or her head in a dark place in his or her abdomen. I've been with AT&T for a few years and this is the first time I've experienced this. My bill is paid automatically. What is the reason for this process?!