An initial SIP message is sent to establish a first SIP communication session from a first SIP device. The initial SIP message is sent via a first of a plurality of session managers to a second SIP device. After receiving the initial SIP message at the second SIP device and before ending the first SIP communication session, either the first or second SIP device sends a second SIP message. The second SIP message is sent to the first of the plurality of session managers. Either the first or second SIP devices detects that a response SIP message to the sent second SIP message was not received within a defined time period. In response to detecting that the SIP response message was not received within the defined time period, either the first or second SIP device resends the second SIP message to a second one of the plurality of session managers.