Hi.
I’m sorry, but I didn’t understand your question.
Can you reformulate?
Regards,
Sara

Well, when you want to use this module to send some data to mobile phone by sms you have to write a code and insert this phone number into that code. I hope it is clear so far. BUT when you dont know this number during coding or you will want to change this number in the future (user will change the provider or device will use another person with another phone number), how to do this operation? Without connecting the board to computer and change the number in the code. The phone number where t-call sends sms should be some variable in the code and user could change it by sending sms with some AT command to the t-call module with concrete phone number and it will be written to this variable.
I will explain it again if it wont be clear. Thank you for patiente and help.

Hi.
I think I already answered your question some time ago in our blog.
The library we’re using doesn’t support receiving SMS. So, you’ll need to use AT commands.
We don’t have any example for receiving SMS for that specific module.
I found this discussion in which they provide some examples for receiving SMS: https://www.reddit.com/r/arduino/comments/ovyalp/esp32_sim800l_tcall_receive_sms_tinygsm/
 
I hope this helps.
Regards,
Sara