sst_b2b: added proper sample config for sst

apps/sst_b2b/etc/sst_b2b.conf

@@ -1,8 +1,37 @@
-# session timer configuration:
+# RFC4028 Session Timer
+#
+
+# - enables the session timer ([yes,no]; default: no)
+#
 enable_session_timer=yes
-session_expires=90
-minimum_timer=10
 
+# - set the "Session-Expires" parameter for the session timer.
+#
+# session_expires=240
+
+# - set the "Min-SE" parameter for the session timer.
+#
+# minimum_timer=90
+
+# session refresh (Session Timer, RFC4028) method
+#
+# INVITE                 - use re-INVITE
+# UPDATE                 - use UPDATE
+# UPDATE_FALLBACK_INVITE - use UPDATE if indicated in Allow, re-INVITE otherwise
+#
+# Default: UPDATE_FALLBACK_INVITE
+#
+# Note: Session Timers are only supported in some applications
+#
+#session_refresh_method=UPDATE
+
+# accept_501_reply - accept 501 reply as successful refresh? [yes|no]
+#
+# Default: yes
+#
+#accept_501_reply=no
+
+######################################################
 #authentication (questionable whether that works)
 # user=someuser
 # domain=somedomain.net