We like the functionality of Call completed elsewhere in ring groups as sip client doesn't show missed call in call log.

Is there a way to fake SIP CANCEL later? 

For example, let's say call rings on 5 phones, and no one answers. After that, someone calls this number back and we would like to inform all the other 4 phones that this missed call was answered. Sip client groups all calls from/to one number and doesn't show missed call, if it was answered later, same as on cell phones.

BR, Gregor