There is a link here:
The link is this one:
https://fccid.io/2AON8-BM818/Users-Manual/BM818-Coperation-manual-V1-4-4107101
“BM818 LTE Wireless Module User Manual BM818 Coperation manual_V1.4 Shanghai Broadmobi communication Technology LTd
Shanghai Broadmobi communication Technology LTd LTE Wireless Module”
Same thing as pdf:
https://fccid.io/2AON8-BM818/User-Manual/BM818-Coperation-manual-V1-4-4107101.pdf