Text message on Log

My text message log (when I go to usage on Verizonwireless.com) shows there’s a random Nevada number that sent me texts but I never received them?? 

I called the number and it’s a landline??

I talked to a Verizon rep and he said that Verizon has been automatically blocking any known spam/robo texts from coming in. So there might be random numbers in the text log of texts not received. 

Is this true?