A UAC or a User Agent Server (UAS) may specify the flow to send messages on by using one of the following methods.

• SipSession.setFlow(Flow flow).

• Proxy.setFlow(Flow flow)

• ProxyBranch.setFlow(Flow flow)

For example, a UAC can specify that the same flow that is used for sending REGISTER messages be used for sending INVITE messages as shown in Example 8-3.

void sendInvite(SipServletRequest invite){
  Flow flow = // Retrieve the flow...
  invite.getSession().setFlow(flow);
  invite.send();
}