Thanks for your answer. I'm just trying to register a phone to multiple openser, for load balancing, instead of having a single usrloc database. The doc of tm module about t_replicate says that: "No information due the replicated request (like reply code) will be forwarded to the original SIP UAC." So it's seems that there should be no problems about reply code, but if ser makes a fork, only a single t_replicate is possible. What am I missing?