A method of operating a push-to-talk service over a mobile wireless communication network, where a user of a mobile wireless terminal may select an automatic or manual answer mode for incoming session invitations for at least some other users. The method comprises including in the push-to-talk session invitation sent from a calling party to a called party, a manual answer mode request, upon receipt of the session invitation at a push-to-talk server serving the called party, forwarding the invitation including the manual answer mode request to the called party regardless of any auto-answer mode setting for the called party, and receiving the invitation at the called party, and generating a ringing alert at the called party's terminal.