EC2X PCM function

Dear Quectel Team,

We’re choosing mobile chip for our project. We need 4G module with ability to receive/transfer PCM streams for microphone and speaker audio. We’re doing research on EC20, EC21 & EC200 modules. Their datasheets have PCM function with “optional” remark.
Does it mean that these modules don’t have PCM function by default in hardware? If yes, how can we be sure that ordered chips have such function? Could you please give an explanation?

Thanks in advance.

Dear Quectel Team,

I look forward to hearing from you.

Dear Quectel Team,

I wait for you support, thanks.