Does the IP address over a mobile data connection (gprs, 3g/4g) change every time on new connection? Is the IP address of a data connection assigned every time whenever a fresh connection is established (e.g after a  disconnect-reconnect scenario, reboot etc) or its preserved.

I have done a bit of research on this topic but there are slightly different views. The first one is affirmative:


  Whether the IP address is reachable from the public Internet, however,
  depends on your ISP; most mobile ISPs operate a NAT that multiplexes
  several network-internal IP addresses through a single address visible
  to the public Internet. The externally visible IP address may change
  on the fly as you move around from cell tower to cell tower. Your external IP will, however, change when you reconnect to your network 1


On the other hand, some suggest that the same IP address is maintained even on reconnection after reboot but only changes when the lease expires


  Phones use DHCP (Dynamic Host Control Protocol) to obtain new IP
  addresses from the carrier when the lease on the address expires. You
  don't get a new IP address every time the phone reboots, only when you
  restart the phone and the lease on the IP address has expired. 2


I do understand the concept of DHCP and that new IP  addreses are assigned whenever the lease expires (some suggest usually after 24 hours or so) but my confusion is that if the lease is still valid and I do disconnect and reconnect mobile data, do I get assigned a new IP or the existing one is kept?

References


Does my phone have an IP address when I'm using the internet, but not connected to WiFi?
Does my 4G mobile phone have a fixed IP address or does it change whenever I move to a different location or whenever I restart the phone?
The answer is this varies by carrier and can vary for any number of other circumstances such as market, locale, and traffic density... Both answers you referenced are correct for certain situations. I have also seen DHCP leases in crowded mobile network areas be under 4 hours... So does your IP address change every time you connect? Sometimes it will, sometimes it won't, there is no definite answer that encompasses all/most situations.