Hi, I am trying to look up information on the use of FreeSWITCH together with OpenSER. I am doing a configuration on my own without much experience on the configuration of OpenSER. In my setup OpensSER acts as a registrar and proxy. I have multiple FreeSWITCH servers for media, routing and PSTN termination, but I am not sure if my approach is the "right way". All SIP traffic goes to the OpenSER proxy which in turn routes the call with the LCR module to a FreeSWITCH server. This has proven to work fine in my limited testing environment. I am using ENUM on the FreeSWITCH server to look up dialed numbers. If the dialed number was found in our ENUM registry and belongs to the proxy, we call back to OpenSER: SIP UA (subscriber 56195122) -> INVITE 25929511 -> FreeSWITCH -> ENUM lookup -> Found -> Routed back to OpenSER -> SIP UA (subscriber (25929511) If the call is not found: SIP UA (subscriber 56195122) -> INVITE 95018615 -> FreeSWITCH -> ENUM lookup -> Not found -> Routed to PSTN gateway or SIP peer I am not using aliases in OpenSER as it seems that ENUM provides the same functionality, but please correct me if I'm wrong. I also made this decision because it seems easier to implement features like call forwarding (unconditional, busy, no answer and timed) in FreeSWITCH rather than in OpenSER. This brings me back to my current issue: Call transfer Outbound and inbound calling with ENUM lookups in FreeSWITCH to my test phones works fine. So does calls to the PSTN gateway. My problem has to do with transfers. I can do a an attended transfer from my Polycom phone when I'm in a call. The second call is set up and I can talk to the person I want to transfer to. I hit the transfer button. Nothing happens, and FS and OpenSER try to look up number_to_transfer_to@openser-registrar. The call is routed to OpenSER which complains that it cannot find the subscriber/alias, which makes sense as there isn't configured an alias. But this also happens when I transfer to a PSTN number. Do I need to take special actions on REFERs? Are there any examples of a working OpenSER + FreeSWITCH setup out there? I believe FreeSWITCH and OpenSER complement each other great but I found the lack of information on the two applications used together a showstopper. Has anyone implemented phone service based on OpenSER and FreeSWITCH who can explain their setup a bit? Regards, Mikael