iana defines these methods:
Methods and Response Codes - per [RFC3261] Section 27.4
--------------------------
Methods Reference
------- ---------
ACK [RFC3261]
BYE [RFC3261]
CANCEL [RFC3261]
INFO [RFC2976]
INVITE [RFC3261]
NOTIFY [RFC3265]
OPTIONS [RFC3261]
PRACK [RFC3262]
REGISTER [RFC3261]
SUBSCRIBE [RFC3265]
UPDATE [RFC3311]
MESSAGE [RFC3428]
REFER [RFC3515]
so perhaps all of them should be include.
-- juha