Assumption: Your surveillance camera is on 24 hours a day and transmits data to the main server. Then the required monthly traffic is calculated like this:
How many gigabytes is the total amount transmitted. does the data have? = Video stream size/8*3600*24*days storage*number of video channels/1024.
Your wireless remote surveillance camera transmits for one month. We calculate it as 30 days. The camera encoding is H265, the bit rate is fixed, and the bit stream size is calculated as 3M.
3/8*3600*24*1*30/1024 = 949.21G
That is: a wireless remote surveillance camera with a card 4G requires around 950G of traffic per month.