I've been using the pipelimit module and the pl_check function to control users rates in my proxy. 

if (!pl_check("$var(UserID)", "TAILDROP", "$var(UserRate)")) {

     pl_drop();

     exit; 

}

In this case  $var(UserID) is the pipe and  $var(UserRate) is the maximum rate.

The value of the rate is retrieved on every call via query to a DB. 

If I change the UserRate value to 0 CPS on the DB calls are not rejected unless they go over 1 CPS. However, if I restart Kamailio all calls are correctly rejected. 

Why does this happen? Can I change this behaviour?

Cheers,

Duarte