diff --git a/core/AmSipDialog.cpp b/core/AmSipDialog.cpp
index 5a37e87d..d31357a4 100644
--- a/core/AmSipDialog.cpp
+++ b/core/AmSipDialog.cpp
@@ -172,7 +172,7 @@ int AmSipDialog::rel100OnRequestIn(const AmSipRequest& req)
   if (req.method == SIP_METH_INVITE) {
     switch(reliable_1xx) {
       case REL100_SUPPORTED: /* if support is on, enforce if asked by UAC */
-        if (key_in_list(getHeader(req.hdrs, SIP_HDR_SUPPORTED), 
+        if (key_in_list(getHeader(req.hdrs, SIP_HDR_SUPPORTED, SIP_HDR_SUPPORTED_COMPACT),
               SIP_EXT_100REL) ||
             key_in_list(getHeader(req.hdrs, SIP_HDR_REQUIRE), 
               SIP_EXT_100REL)) {
@@ -182,7 +182,7 @@ int AmSipDialog::rel100OnRequestIn(const AmSipRequest& req)
         break;
 
       case REL100_REQUIRE: /* if support is required, reject if UAC doesn't */
-        if (! (key_in_list(getHeader(req.hdrs,SIP_HDR_SUPPORTED), 
+        if (! (key_in_list(getHeader(req.hdrs,SIP_HDR_SUPPORTED, SIP_HDR_SUPPORTED_COMPACT),
               SIP_EXT_100REL) ||
             key_in_list(getHeader(req.hdrs, SIP_HDR_REQUIRE), 
               SIP_EXT_100REL))) {
diff --git a/core/AmSipHeaders.h b/core/AmSipHeaders.h
index fea90af3..00b14703 100644
--- a/core/AmSipHeaders.h
+++ b/core/AmSipHeaders.h
@@ -45,6 +45,7 @@
 #define SIP_EXT_100REL          "100rel"
 
 #define SIP_HDR_SESSION_EXPIRES_COMPACT "x"
+#define SIP_HDR_SUPPORTED_COMPACT "k"
 
 #define SIP_IS_200_CLASS(code)  ((code >= 200) && (code < 300))
 
diff --git a/core/plug-in/session_timer/SessionTimer.cpp b/core/plug-in/session_timer/SessionTimer.cpp
index b9778b88..a91668cc 100644
--- a/core/plug-in/session_timer/SessionTimer.cpp
+++ b/core/plug-in/session_timer/SessionTimer.cpp
@@ -270,7 +270,8 @@ void SessionTimer::updateTimer(AmSession* s, const AmSipRequest& req) {
   if((req.method == SIP_METH_INVITE)||(req.method == SIP_METH_UPDATE)){
     
     remote_timer_aware = 
-      key_in_list(getHeader(req.hdrs, SIP_HDR_SUPPORTED), TIMER_OPTION_TAG, true);
+      key_in_list(getHeader(req.hdrs, SIP_HDR_SUPPORTED, SIP_HDR_SUPPORTED_COMPACT),
+		  TIMER_OPTION_TAG, true);
     
     // determine session interval
     string sess_expires_hdr = getHeader(req.hdrs, SIP_HDR_SESSION_EXPIRES,