diff --git a/coreapi/bellesip_sal/sal_op_call.c b/coreapi/bellesip_sal/sal_op_call.c
index 4f416f565..d1fff0d83 100644
--- a/coreapi/bellesip_sal/sal_op_call.c
+++ b/coreapi/bellesip_sal/sal_op_call.c
@@ -773,7 +773,7 @@ static void sal_op_fill_invite(SalOp *op, belle_sip_request_t* invite) {
 	return;
 }
 
-int sal_call(SalOp *op, const char *from, const char *to){
+int sal_call(SalOp *op, const char *from, const char *to, const char *subject){
 	belle_sip_request_t* invite;
 	op->dir=SalOpDirOutgoing;
 
@@ -789,6 +789,8 @@ int sal_call(SalOp *op, const char *from, const char *to){
 	}
 
 	sal_op_fill_invite(op,invite);
+	if (subject)
+		belle_sip_message_add_header(BELLE_SIP_MESSAGE(invite), belle_sip_header_create("Subject", subject));
 
 	sal_op_call_fill_cbs(op);
 	if (op->replaces){
@@ -1036,7 +1038,7 @@ int sal_call_update(SalOp *op, const char *subject, bool_t no_user_consent){
 			during a very early state of outgoing call initiation (the dialog has not been created yet). */
 		const char *from = sal_op_get_from(op);
 		const char *to = sal_op_get_to(op);
-		return sal_call(op, from, to);
+		return sal_call(op, from, to, subject);
 	}
 
 	state = belle_sip_dialog_get_state(op->dialog);
diff --git a/coreapi/chat.c b/coreapi/chat.c
index 7059cb04b..a458facac 100644
--- a/coreapi/chat.c
+++ b/coreapi/chat.c
@@ -125,8 +125,8 @@ LinphoneChatRoom *linphone_core_get_chat_room(LinphoneCore *lc, const LinphoneAd
 	return ret;
 }
 
-LinphoneChatRoom * linphone_core_create_client_group_chat_room(LinphoneCore *lc) {
-	LinphoneChatRoom *cr = _linphone_client_group_chat_room_new(lc);
+LinphoneChatRoom * linphone_core_create_client_group_chat_room(LinphoneCore *lc, const char *subject) {
+	LinphoneChatRoom *cr = _linphone_client_group_chat_room_new(lc, subject);
 	lc->chatrooms = bctbx_list_append(lc->chatrooms, cr);
 	return cr;
 }
diff --git a/coreapi/private.h b/coreapi/private.h
index b3a9d0ce7..80cea1623 100644
--- a/coreapi/private.h
+++ b/coreapi/private.h
@@ -460,7 +460,7 @@ void _linphone_proxy_config_release_ops(LinphoneProxyConfig *obj);
 
 /*chat*/
 LinphoneChatRoom * linphone_chat_room_new(LinphoneCore *core, const LinphoneAddress *addr);
-LinphoneChatRoom *_linphone_client_group_chat_room_new(LinphoneCore *core);
+LinphoneChatRoom *_linphone_client_group_chat_room_new (LinphoneCore *core, const char *subject);
 void linphone_chat_room_release(LinphoneChatRoom *cr);
 void linphone_chat_room_set_call(LinphoneChatRoom *cr, LinphoneCall *call);
 bctbx_list_t * linphone_chat_room_get_transient_messages(const LinphoneChatRoom *cr);
diff --git a/coreapi/sal/sal.h b/coreapi/sal/sal.h
index bcda97dde..5e0188feb 100644
--- a/coreapi/sal/sal.h
+++ b/coreapi/sal/sal.h
@@ -742,7 +742,7 @@ void sal_op_set_event(SalOp *op, const char *event);
 
 /*Call API*/
 int sal_call_set_local_media_description(SalOp *h, SalMediaDescription *desc);
-int sal_call(SalOp *h, const char *from, const char *to);
+int sal_call(SalOp *h, const char *from, const char *to, const char *subject);
 int sal_call_notify_ringing(SalOp *h, bool_t early_media);
 /*accept an incoming call or, during a call accept a reINVITE*/
 int sal_call_accept(SalOp*h);
diff --git a/include/linphone/core.h b/include/linphone/core.h
index 231557035..55b6fc282 100644
--- a/include/linphone/core.h
+++ b/include/linphone/core.h
@@ -4837,9 +4837,10 @@ LINPHONE_PUBLIC const char *linphone_core_get_chat_database_path(const LinphoneC
  * at the client-side and is empty. Pou need to call linphone_chat_room_add_participants() to
  * create at the server side and add participants to it.
  * @param[in] lc A #LinphoneCore object
+ * @param[in] subject The subject of the group chat room
  * @return The newly created client-side group chat room.
  */
-LINPHONE_PUBLIC LinphoneChatRoom * linphone_core_create_client_group_chat_room(LinphoneCore *lc);
+LINPHONE_PUBLIC LinphoneChatRoom * linphone_core_create_client_group_chat_room(LinphoneCore *lc, const char *subject);
 
 /**
  * Get a chat room whose peer is the supplied address. If it does not exist yet, it will be created.
diff --git a/src/address/address.cpp b/src/address/address.cpp
index 17b9ed9bf..8de8d1f90 100644
--- a/src/address/address.cpp
+++ b/src/address/address.cpp
@@ -67,6 +67,10 @@ bool Address::operator== (const Address &address) const {
 	return equal(address);
 }
 
+bool Address::operator< (const Address &address) const {
+	return asString() < address.asString();
+}
+
 bool Address::isValid () const {
 	L_D(const Address);
 	return static_cast<bool>(d->internalAddress);
diff --git a/src/address/address.h b/src/address/address.h
index 679ba572b..eb3d74ed0 100644
--- a/src/address/address.h
+++ b/src/address/address.h
@@ -38,6 +38,8 @@ public:
 
 	bool operator== (const Address &address) const;
 
+	bool operator< (const Address &address) const;
+
 	bool isValid () const;
 
 	const std::string &getScheme () const;
diff --git a/src/c-wrapper/api/c-chat-room.cpp b/src/c-wrapper/api/c-chat-room.cpp
index 652ccb466..558b8e56c 100644
--- a/src/c-wrapper/api/c-chat-room.cpp
+++ b/src/c-wrapper/api/c-chat-room.cpp
@@ -277,7 +277,7 @@ LinphoneChatRoom *linphone_chat_room_new (LinphoneCore *core, const LinphoneAddr
 	return cr;
 }
 
-LinphoneChatRoom *_linphone_client_group_chat_room_new (LinphoneCore *core) {
+LinphoneChatRoom *_linphone_client_group_chat_room_new (LinphoneCore *core, const char *subject) {
 	const char *factoryUri = linphone_core_get_conference_factory_uri(core);
 	if (!factoryUri)
 		return nullptr;
@@ -291,7 +291,7 @@ LinphoneChatRoom *_linphone_client_group_chat_room_new (LinphoneCore *core) {
 		from = linphone_core_get_primary_contact(core);
 	LinphonePrivate::Address me(from);
 	LinphoneChatRoom *cr = L_INIT(ChatRoom);
-	L_SET_CPP_PTR_FROM_C_OBJECT(cr, make_shared<LinphonePrivate::ClientGroupChatRoom>(core, me));
+	L_SET_CPP_PTR_FROM_C_OBJECT(cr, make_shared<LinphonePrivate::ClientGroupChatRoom>(core, me, subject ? subject : ""));
 	L_GET_PRIVATE_FROM_C_OBJECT(cr)->setState(LinphonePrivate::ChatRoom::State::Instantiated);
 	return cr;
 }
diff --git a/src/call/call.cpp b/src/call/call.cpp
index 9c9e6f613..929bfceca 100644
--- a/src/call/call.cpp
+++ b/src/call/call.cpp
@@ -97,7 +97,7 @@ void CallPrivate::startIncomingNotification () {
 }
 
 int CallPrivate::startInvite (const Address *destination) {
-	return getActiveSession()->startInvite(destination);
+	return getActiveSession()->startInvite(destination, "");
 }
 
 // -----------------------------------------------------------------------------
diff --git a/src/chat/client-group-chat-room-p.h b/src/chat/client-group-chat-room-p.h
index 346faf869..ef642bc6c 100644
--- a/src/chat/client-group-chat-room-p.h
+++ b/src/chat/client-group-chat-room-p.h
@@ -31,10 +31,12 @@ LINPHONE_BEGIN_NAMESPACE
 
 class ClientGroupChatRoomPrivate : public ChatRoomPrivate {
 public:
-	ClientGroupChatRoomPrivate (LinphoneCore *core);
+	ClientGroupChatRoomPrivate (LinphoneCore *core, const std::string &subject);
 	virtual ~ClientGroupChatRoomPrivate () = default;
 
 private:
+	std::string subject;
+
 	L_DECLARE_PUBLIC(ClientGroupChatRoom);
 };
 
diff --git a/src/chat/client-group-chat-room.cpp b/src/chat/client-group-chat-room.cpp
index 912383cf4..bfd078e57 100644
--- a/src/chat/client-group-chat-room.cpp
+++ b/src/chat/client-group-chat-room.cpp
@@ -19,6 +19,7 @@
 #include "client-group-chat-room-p.h"
 #include "c-wrapper/c-wrapper.h"
 #include "conference/participant-p.h"
+#include "content/content.h"
 #include "logger/logger.h"
 
 // =============================================================================
@@ -27,18 +28,15 @@ using namespace std;
 
 LINPHONE_BEGIN_NAMESPACE
 
-ClientGroupChatRoomPrivate::ClientGroupChatRoomPrivate (LinphoneCore *core) : ChatRoomPrivate(core) {}
+ClientGroupChatRoomPrivate::ClientGroupChatRoomPrivate (LinphoneCore *core, const string &subject)
+	: ChatRoomPrivate(core), subject(subject) {}
 
 // =============================================================================
 
-ClientGroupChatRoom::ClientGroupChatRoom (LinphoneCore *core, const Address &me)
-	: ChatRoom(*new ChatRoomPrivate(core)), RemoteConference(core, me, nullptr) {
+ClientGroupChatRoom::ClientGroupChatRoom (LinphoneCore *core, const Address &me, const string &subject)
+	: ChatRoom(*new ClientGroupChatRoomPrivate(core, subject)), RemoteConference(core, me, nullptr) {
 	string factoryUri = linphone_core_get_conference_factory_uri(core);
 	focus = make_shared<Participant>(factoryUri);
-	CallSessionParams csp;
-	shared_ptr<CallSession> session = focus->getPrivate()->createSession(*this, &csp, false, this);
-	session->configure(LinphoneCallOutgoing, nullptr, nullptr, me, focus->getAddress());
-	// TODO
 }
 
 // -----------------------------------------------------------------------------
@@ -51,10 +49,25 @@ shared_ptr<Participant> ClientGroupChatRoom::addParticipant (const Address &addr
 
 void ClientGroupChatRoom::addParticipants (const list<Address> &addresses, const CallSessionParams *params, bool hasMedia) {
 	L_D(ClientGroupChatRoom);
+	if (addresses.empty())
+		return;
+	list<Address> sortedAddresses(addresses);
+	sortedAddresses.sort();
+	sortedAddresses.unique();
 	if (d->state == ChatRoom::State::Instantiated) {
-		shared_ptr<CallSession> session = focus->getPrivate()->getSession();
+		Content content;
+		content.setBody(getResourceLists(sortedAddresses));
+		content.setContentType("application/resource-lists+xml");
+		content.setContentDisposition("recipient-list");
+		lInfo() << "Body size: " << content.getSize() << endl << "Body:" << endl << content.getBodyAsString();
+		CallSessionParams csp;
+		if (params)
+			csp = *params;
+		csp.addCustomHeader("Require", "recipient-list-invite");
+		shared_ptr<CallSession> session = focus->getPrivate()->createSession(*this, &csp, false, this);
+		session->configure(LinphoneCallOutgoing, nullptr, nullptr, me->getAddress(), focus->getAddress());
 		session->initiateOutgoing();
-		session->startInvite(nullptr);
+		session->startInvite(nullptr, d->subject);
 		d->setState(ChatRoom::State::CreationPending);
 	}
 	// TODO
diff --git a/src/chat/client-group-chat-room.h b/src/chat/client-group-chat-room.h
index 8207b62dd..eab0f5a28 100644
--- a/src/chat/client-group-chat-room.h
+++ b/src/chat/client-group-chat-room.h
@@ -36,7 +36,7 @@ class ClientGroupChatRoomPrivate;
 
 class ClientGroupChatRoom : public ChatRoom, public RemoteConference {
 public:
-	ClientGroupChatRoom (LinphoneCore *core, const Address &me);
+	ClientGroupChatRoom (LinphoneCore *core, const Address &me, const std::string &subject);
 	virtual ~ClientGroupChatRoom () = default;
 
 public:
diff --git a/src/conference/session/call-session.cpp b/src/conference/session/call-session.cpp
index d38fa5e85..64af9041d 100644
--- a/src/conference/session/call-session.cpp
+++ b/src/conference/session/call-session.cpp
@@ -311,7 +311,7 @@ void CallSessionPrivate::pingReply () {
 	if (state == LinphoneCallOutgoingInit) {
 		pingReplied = true;
 		if (isReadyForInvite())
-			q->startInvite(nullptr);
+			q->startInvite(nullptr, "");
 	}
 }
 
@@ -770,7 +770,7 @@ void CallSession::iterate (time_t currentRealTime, bool oneSecondElapsed) {
 	int elapsed = (int)(currentRealTime - d->log->start_date_time);
 	if ((d->state == LinphoneCallOutgoingInit) && (elapsed >= d->core->sip_conf.delayed_timeout)) {
 		/* Start the call even if the OPTIONS reply did not arrive */
-		startInvite(nullptr);
+		startInvite(nullptr, "");
 	}
 	if ((d->state == LinphoneCallIncomingReceived) || (d->state == LinphoneCallIncomingEarlyMedia)) {
 		if (oneSecondElapsed)
@@ -828,7 +828,7 @@ void CallSession::startIncomingNotification () {
 	}
 }
 
-int CallSession::startInvite (const Address *destination) {
+int CallSession::startInvite (const Address *destination, const string &subject) {
 	L_D(CallSession);
 	/* Try to be best-effort in giving real local or routable contact address */
 	d->setContactOp();
@@ -844,7 +844,7 @@ int CallSession::startInvite (const Address *destination) {
 	char *from = linphone_address_as_string(d->log->from);
 	/* Take a ref because sal_call() may destroy the CallSession if no SIP transport is available */
 	shared_ptr<CallSession> ref = static_pointer_cast<CallSession>(shared_from_this());
-	int result = sal_call(d->op, from, destinationStr.c_str());
+	int result = sal_call(d->op, from, destinationStr.c_str(), subject.empty() ? nullptr : subject.c_str());
 	ms_free(from);
 	if (result < 0) {
 		if ((d->state != LinphoneCallError) && (d->state != LinphoneCallReleased)) {
diff --git a/src/conference/session/call-session.h b/src/conference/session/call-session.h
index 96dcbf2bf..07f8ab262 100644
--- a/src/conference/session/call-session.h
+++ b/src/conference/session/call-session.h
@@ -47,7 +47,7 @@ public:
 	virtual bool initiateOutgoing ();
 	virtual void iterate (time_t currentRealTime, bool oneSecondElapsed);
 	virtual void startIncomingNotification ();
-	virtual int startInvite (const Address *destination);
+	virtual int startInvite (const Address *destination, const std::string &subject);
 	LinphoneStatus terminate (const LinphoneErrorInfo *ei = nullptr);
 	LinphoneStatus update (const CallSessionParams *csp);
 
diff --git a/src/conference/session/media-session.cpp b/src/conference/session/media-session.cpp
index c1bce3c98..c19d8d9ce 100644
--- a/src/conference/session/media-session.cpp
+++ b/src/conference/session/media-session.cpp
@@ -2090,7 +2090,7 @@ void MediaSessionPrivate::handleIceEvents (OrtpEvent *ev) {
 			case LinphoneCallOutgoingInit:
 				stopStreamsForIceGathering();
 				if (isReadyForInvite())
-					q->startInvite(nullptr);
+					q->startInvite(nullptr, "");
 				break;
 			case LinphoneCallIdle:
 				stopStreamsForIceGathering();
@@ -4249,7 +4249,7 @@ void MediaSession::startIncomingNotification () {
 	CallSession::startIncomingNotification();
 }
 
-int MediaSession::startInvite (const Address *destination) {
+int MediaSession::startInvite (const Address *destination, const string &subject) {
 	L_D(MediaSession);
 	linphone_core_stop_dtmf_stream(d->core);
 	d->makeLocalMediaDescription();
@@ -4265,7 +4265,7 @@ int MediaSession::startInvite (const Address *destination) {
 		sal_call_set_local_media_description(d->op, d->localDesc);
 	}
 
-	int result = CallSession::startInvite(destination);
+	int result = CallSession::startInvite(destination, subject);
 	if (result < 0) {
 		if (d->state == LinphoneCallError)
 			d->stopStreams();
diff --git a/src/conference/session/media-session.h b/src/conference/session/media-session.h
index e27c1c7e2..27770ebb1 100644
--- a/src/conference/session/media-session.h
+++ b/src/conference/session/media-session.h
@@ -48,7 +48,7 @@ public:
 	LinphoneStatus resume ();
 	void sendVfuRequest ();
 	void startIncomingNotification () override;
-	int startInvite (const Address *destination) override;
+	int startInvite (const Address *destination, const std::string &subject) override;
 	void startRecording ();
 	void stopRecording ();
 	LinphoneStatus update (const MediaSessionParams *msp);