diff --git a/apps/sbc/SBCCallLeg.cpp b/apps/sbc/SBCCallLeg.cpp
index 62009313..6d7c363c 100644
--- a/apps/sbc/SBCCallLeg.cpp
+++ b/apps/sbc/SBCCallLeg.cpp
@@ -804,11 +804,19 @@ void SBCCallLeg::onSendRequest(AmSipRequest& req, int &flags) {
 
   CallLeg::onSendRequest(req, flags);
 
-  /* check whether SST related headers must be removed before sending out */
-  if (!sessionTimerSupportedByLeg(call_profile, a_leg)) {
-    ILOG_DLG(L_DBG, "SST isn't supported by '%c' leg, remove according headers and option tags.\n",
-             a_leg ? 'A' : 'B');
-    removeSessionTimerHeaders(req.hdrs);
+  /* clean SST related headers if not supported by the receiving leg
+   * but only if the mode isn't transparent */
+  if (!call_profile.sst_transparent) {
+    /* check whether SST related headers must be removed before sending out */
+    if (!sessionTimerSupportedByLeg(call_profile, a_leg)) {
+      ILOG_DLG(L_DBG, "SST isn't supported by '%c' leg, remove according headers and option tags.\n",
+              a_leg ? 'A' : 'B');
+      removeSessionTimerHeaders(req.hdrs);
+    }
+  }
+  else {
+    ILOG_DLG(L_DBG, "Transparent SST mode enabled globally, ignore SST headers for '%c' leg.\n",
+              a_leg ? 'A' : 'B');
   }
 }
 
@@ -816,11 +824,19 @@ void SBCCallLeg::onSendReply(const AmSipRequest& req, AmSipReply& reply, int &fl
 {
   CallLeg::onSendReply(req, reply, flags);
 
-  /* check whether SST related headers must be removed before sending out */
-  if (!sessionTimerSupportedByLeg(call_profile, a_leg)) {
-    ILOG_DLG(L_DBG, "SST isn't supported by '%c' leg, remove according headers and option tags.\n",
-             a_leg ? 'A' : 'B');
-    removeSessionTimerHeaders(reply.hdrs);
+  /* clean SST related headers if not supported by the receiving leg
+   * but only if the mode isn't transparent */
+  if (!call_profile.sst_transparent) {
+    /* check whether SST related headers must be removed before sending out */
+    if (!sessionTimerSupportedByLeg(call_profile, a_leg)) {
+      ILOG_DLG(L_DBG, "SST isn't supported by '%c' leg, remove according headers and option tags.\n",
+              a_leg ? 'A' : 'B');
+      removeSessionTimerHeaders(reply.hdrs);
+    }
+  }
+  else {
+    ILOG_DLG(L_DBG, "Transparent SST mode enabled globally, ignore SST headers for '%c' leg.\n",
+              a_leg ? 'A' : 'B');
   }
 }
 
diff --git a/apps/sbc/SBCCallProfile.cpp b/apps/sbc/SBCCallProfile.cpp
index 58e9638e..0bd99877 100644
--- a/apps/sbc/SBCCallProfile.cpp
+++ b/apps/sbc/SBCCallProfile.cpp
@@ -204,6 +204,9 @@ bool SBCCallProfile::readFromConfiguration(const string& name,
     return false;
 
   sst_enabled = cfg.getParameter("enable_session_timer");
+
+  sst_transparent = cfg.getParameter("session_timer_transparent", "no") == "yes";
+
   if (cfg.hasParameter("enable_aleg_session_timer")) {
     sst_aleg_enabled = cfg.getParameter("enable_aleg_session_timer");
   } else {
@@ -544,6 +547,7 @@ bool SBCCallProfile::readFromConfiguration(const string& name,
 
     INFO("SBC:      SST on A leg enabled: '%s'\n", sst_aleg_enabled.empty() ?
 	 "no" : sst_aleg_enabled.c_str());
+    INFO("SBC:      SST transparent mode: %s\n", sst_transparent ? "yes" : "no");
     if (sst_aleg_enabled.size() && sst_aleg_enabled != "no") {
       INFO("SBC:              session_expires=%s\n",
 	   sst_a_cfg.getParameter("session_expires").c_str());
@@ -652,6 +656,7 @@ bool SBCCallProfile::operator==(const SBCCallProfile& rhs) const {
     sdpfilter == rhs.sdpfilter &&
     aleg_sdpfilter == rhs.aleg_sdpfilter &&
     mediafilter == rhs.mediafilter &&
+    sst_transparent == rhs.sst_transparent &&
     sst_enabled == rhs.sst_enabled &&
     sst_aleg_enabled == rhs.sst_aleg_enabled &&
     auth_enabled == rhs.auth_enabled &&
diff --git a/apps/sbc/SBCCallProfile.h b/apps/sbc/SBCCallProfile.h
index 0b656abb..a2dd0051 100644
--- a/apps/sbc/SBCCallProfile.h
+++ b/apps/sbc/SBCCallProfile.h
@@ -142,6 +142,7 @@ struct SBCCallProfile
   vector<FilterEntry> sdpalinesfilter;
   vector<FilterEntry> mediafilter;
 
+  bool sst_transparent;
   string sst_enabled;
   bool sst_enabled_value;
   string sst_aleg_enabled;
@@ -353,6 +354,7 @@ struct SBCCallProfile
     allow_subless_notify(false),
     anonymize_sdp(false),
     have_aleg_sdpfilter(false),
+    sst_transparent(false),
     sst_enabled_value(false),
     auth_aleg_enabled(false),
     uas_auth_bleg_enabled(false),
diff --git a/apps/sbc/etc/sbc.conf b/apps/sbc/etc/sbc.conf
index e67ca8f6..e2336d50 100644
--- a/apps/sbc/etc/sbc.conf
+++ b/apps/sbc/etc/sbc.conf
@@ -69,6 +69,13 @@ active_profile=transparent
 #
 #accept_501_reply=no
 
+# session_timer_transparent - do not strip SST headers or timer option
+# tags while relaying SIP messages to legs without SST support.
+#
+# Default: no
+#
+#session_timer_transparent=no
+
 # sst_strict_mode - disable session timers for a leg if an INVITE/UPDATE
 # request or a positive response does not declare "Supported: timer".
 #