lazedo: so, im not exactly sure what it is between polycom 5.3 and 5.4 firmware - if you're using parkedCallRetrieveMethod (or directedPickupMethod) of "native", which tells it to send the Replaces header - on firmware prior to 5.4, it actually sends sip:kfp+UUID in the "To:" header. In 5.4, it sends "*31" - the kamailio code that looks for ~ru containing sip:kfp+ at the beginning DOES work. However, since the vvx in 5.4+ doesnt send sip:kfp+ any more
(maybe changeable in config?) that code doesnt execute, and instead it executes the block i linked to in github, line 39. And, it fails.