On Fri, Sep 30, 2016 at 10:29:16PM +0530, Infinicalls Infinicalls wrote: Not much important stuff to censor. LBIPADDR is the ipadress of the machine itself. REGISTRARNET/30 is the net of the backend machines. The dispatcher.list contains the backend registrars The backend is essentially the default config (with an always on rtpengine) with the following additions: You need to enable path.so and set modparam("path", "use_received", 1) Tell the registrar module to use path (path_mode 1 fixes you 420 problem): modparam("registrar", "use_path", 1) modparam("registrar", "path_mode", 1) modparam("registrar", "path_use_received", 1) If you want to send keepalives from the registrar to the enduser: modparam("nathelper", "ping_nated_only", 0) modparam("nathelper", "udpping_from_path", 1) the loadbalancer config has a little blurb about relaying the sipping from the backend manually using the path header. But I'd advice to ping from the an external process to have better control (eg sipsak)