[SR-Dev] register_timer versus register_timer_process

Hello, There are two functions in the implementation of timers in kamailio, register_timer and register_timer_process. What is the different between those two functions and which should be used when? I noticed that, for example, the htable module seems to be using them interchangeably, there is a modparam which controls which function is gonna be used. Can we replace register_timer_process with register_timer function from the sip-router core? thanks, Jan.