Honesty Net Solution Pvt.Ltd is one of the ISP (which I used) provide public IP (even open port 80, 8000, 9999, 9000) without any charges.
I used to host FTP server and even my own personal Minecraft room
.
Edited: But my local ISP now changed the main line from HNS to some shitty Gazon Communications India Ltd which uses CG-NAT.