nathelper readme on this flag tells:
What branch flag should be used by the module to disable NAT pings on a per-registration basis. If the given flag is set for a particular registration, then no NAT pings will be sent at all, regardless of any other conditions.
however, the name of the flag is sipping_disable_bflag, which indicates that it would apply to nat ping via sip requests only.
which way it is? please either fix the name of the flag or readme text.
-- juha