As we know, Asterisk supports SIP INFO method - at least, for DTMF processing.
However, I found out that Asterisk does not include INFO in Allow header even if DTMF method is set as “info” for the respective endpoint.
This violates RFC3261, section 20.5:
All methods, including ACK and CANCEL, understood by the UA MUST be included in the list of methods in the Allow header field
Is it a bug, a feature or a configurable item?
P.S. Asterisk 13.23, PJSIP channel driver.