EC25 save incomming call to file

How can I play a sound file when calling and save incoming voice call to the file like answering machine on QuecOpen

Dear Vahid,
Thanks for your inquiry in Quectel forum.
For your issue, please check the following document. Thanks!
Quectel_WCDMA&LTE_Audio_Design_Note_V1.2_20170723.pdf (1.5 MB)
If you want to play a file when calling, please check the following command in the above document. Thanks!
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Thanks Kyson.
Is there any way to read stream of audio and send stream of audio with C API?

If you want to read the audio, you also can check the file that i have sent to you. And about the C API, you need to develop it by yourself. Thanks!