Roaming behavior

Can somebody explain to me the behavior of the gsm device when it exits the country and enters roaming and then after a few days it reenters the country, but the sim doesn’t have roaming activated(when it leaves the country)? I am sending some data via http that is working just fine while in the country but when the device reenters the country after being outside of the country whit no roaming, the http transmissions doesn’t continue. Is there a reason for this behavior? I am assuming that by exiting the country the device (sim) not having roaming will act just like when entering a region with no signal, am i right?