Hi all.

I use topoh module for topology hiding and this is my config for topoh:

modparam("topoh", "mask_key", "my key")
modparam("topoh", "mask_callid", 1)
modparam("topoh", "callid_prefix", "!!:")
modparam("topoh", "sanity_checks", 1)
modparam("topoh", "mask_ip", "x.x.x.x")
modparam("topoh", "uri_prefix_checks", 1)
modparam("topoh", "uparam_name", "line")
modparam("topoh", "uparam_prefix", "sr-")
modparam("topoh", "vparam_name", "branch")
modparam("topoh", "vparam_prefix", "z9hG4bKsr-")

and also i use:

modparam("dialog", "lreq_callee_headers", "TH: dlh\r\n")

for dialog module.

my calls come from asterisk and routed to the carrier(sip trunk) and vice versa,
when i make a call from asterisk every thing works fine until the call hanged up from the carrier. at that modemt the kamailio send an 481 call/leg transaction does not exist.
if call dropped bye the asterisk user everything works fine.
how can i solve this?