diff --git a/apps/dsm/DSMCall.cpp b/apps/dsm/DSMCall.cpp
index f7d2151b..4758439a 100644
--- a/apps/dsm/DSMCall.cpp
+++ b/apps/dsm/DSMCall.cpp
@@ -633,6 +633,23 @@ void DSMCall::process(AmEvent* event)
     }
   }
 
+  B2BEvent* b2b_ev = dynamic_cast<B2BEvent*>(event);
+  if (b2b_ev) {
+    string pai_from_hdr = getVar(DSM_B2B_BUILD_PAI_FROM_HDR);
+    if (b2b_ev->event_id == B2BSipReply && !pai_from_hdr.empty()) {
+      string pai_value;
+      B2BgetHeaderReply(pai_from_hdr, pai_value);
+      DBG("Building '%s' value from header '%s'.\n", SIP_HDR_P_ASSERTED_IDENTITY, pai_from_hdr.c_str());
+      if (!pai_value.empty()) {
+        DBG("Passing '%s' with value '%s' to B2BSipReply handling.\n", SIP_HDR_P_ASSERTED_IDENTITY, pai_value.c_str());
+        /* CRLF required later for reinviteCaller(), dlg->sendRequest() */
+        b2b_ev->params["hdrs"] = SIP_HDR_COLSP(SIP_HDR_P_ASSERTED_IDENTITY) + pai_value + CRLF;
+      } else {
+        DBG("Impossible to get the value of '%s'.\n", pai_from_hdr.c_str());
+      }
+    }
+  }
+
   AmB2BCallerSession::process(event);
 }
 
diff --git a/apps/dsm/DSMSession.h b/apps/dsm/DSMSession.h
index f686a5c0..b17ceb86 100644
--- a/apps/dsm/DSMSession.h
+++ b/apps/dsm/DSMSession.h
@@ -68,6 +68,8 @@ using std::map;
 
 #define DSM_B2B_CALLID       "b2b_callid"
 
+#define DSM_B2B_BUILD_PAI_FROM_HDR       "b2b_build_pai_from_hdr"
+
 #define DSM_AVAR_REQUEST "request"
 #define DSM_AVAR_REPLY   "reply"
 
diff --git a/core/AmB2BSession.cpp b/core/AmB2BSession.cpp
index b991fdc2..e2919301 100644
--- a/core/AmB2BSession.cpp
+++ b/core/AmB2BSession.cpp
@@ -1326,6 +1326,15 @@ void AmB2BCallerSession::onB2BEvent(B2BEvent* ev)
       case Ringing:
         if (reply.cseq == invite_req.cseq) {
 
+          /* get possibly passed headers for updates towards caller */
+          string hdrs;
+          map<string,string>::const_iterator hdrs_it;
+          hdrs_it = ((B2BSipReplyEvent*)ev)->params.find("hdrs");
+          if (hdrs_it != ((B2BSipReplyEvent*)ev)->params.end()) {
+            hdrs = hdrs_it->second;
+            DBG("Got some headers, which can later be used for re-inviting the caller: '%s'\n", hdrs.c_str());
+          }
+
           if (reply.code < 200) {
             if ((!sip_relay_only) &&
                 (reply.code>=180 && reply.code<=183 && (!reply.body.empty()))) {
@@ -1334,7 +1343,7 @@ void AmB2BCallerSession::onB2BEvent(B2BEvent* ev)
               updateSessionDescription(reply.body);
 
               if (sip_relay_early_media_sdp) {
-                if (reinviteCaller(reply)) {
+                if (reinviteCaller(reply, hdrs)) {
                   ERROR("re-INVITEing caller for early session failed - stopping this and other leg\n");
                   terminateOtherLeg();
                   terminateLeg();
@@ -1362,7 +1371,7 @@ void AmB2BCallerSession::onB2BEvent(B2BEvent* ev)
                 n_reply.body = established_body;
               }
 
-              if (reinviteCaller(n_reply)) {
+              if (reinviteCaller(reply, hdrs)) {
                 ERROR("re-INVITEing caller failed - stopping this and other leg\n");
                 terminateOtherLeg();
                 terminateLeg();
@@ -1500,11 +1509,11 @@ void AmB2BCallerSession::connectCallee(const string& remote_party,
   callee_status = NoReply;
 }
 
-int AmB2BCallerSession::reinviteCaller(const AmSipReply& callee_reply)
+int AmB2BCallerSession::reinviteCaller(const AmSipReply& callee_reply, const string& hdrs)
 {
   return dlg->sendRequest(SIP_METH_INVITE,
 			 &callee_reply.body,
-			 "" /* hdrs */, SIP_FLAGS_VERBATIM);
+			 hdrs, SIP_FLAGS_VERBATIM);
 }
 
 void AmB2BCallerSession::createCalleeSession() {
diff --git a/core/AmB2BSession.h b/core/AmB2BSession.h
index c68d91bc..8c6c3322 100644
--- a/core/AmB2BSession.h
+++ b/core/AmB2BSession.h
@@ -404,7 +404,7 @@ class AmB2BCallerSession: public AmB2BSession
   // Callee Status
   CalleeStatus callee_status;
   
-  int  reinviteCaller(const AmSipReply& callee_reply);
+  int  reinviteCaller(const AmSipReply& callee_reply, const string& hdrs = "");
 
  protected:
   AmSipRequest invite_req;