After an core reload (on asterisk 10.7.0 / FreePBX distro) the registration Call-ID changes (new CSeq).
This behavior causes problems with our sip provider. Every time a core reload has been given this is a new binding. So for incomming calls this is one INVITE per binding (as long as the expire time is set for the former registration).
We think this behavior was different in asterisk 1.4 because we never had complaints about strange behavior after reloading asterisk.
Would it be possilble to keep the same Call-ID after an core reload or set a static Call-ID.
Also see ticket freepbx.org/trac/ticket/5967