Asterisk sip publish method

To all the experts,

I recently run into a situation where I disconnect the call before the receiving end pickup. What I observed was that Asterisk responded with PUBLISH message to the receiving UA, but the UA either can not respond to the “PUBLISH” method or responding with 501 (not implemented). This cause the receiving UA keep on ringing untill I pick up the phone. Is this the normal behavior of Asterisk or a miss-configuration somewhere?

Here is the topology

UA1 —> OBP —> Asterisk —> UA2
I am using xpro and cisco7960

Thanks

For those who has read the post,

I found that this stated behavior is associated with the CVS-HEAD version of asterisk. I later on downgraded to 1.0.9, and the call is cancelled successfully.