SIP 302 is a 'Moved Temporarily' response from a SIP server to tell the client (the phone) to go and register against a different SIP server. This is useful to help direct phones to the correct SIP server and to help load balance servers and so on.

FireBrick SIP supports this, both as a server and a client.

Does Not Support 302

freeswitch 1.2.10

Does Support 302

SNOM
FireBrick