diff --git a/hal/inc/hal_socket.h b/hal/inc/hal_socket.h
index e1d02bb6..f1545167 100644
--- a/hal/inc/hal_socket.h
+++ b/hal/inc/hal_socket.h
@@ -64,6 +64,15 @@ typedef struct sSocket* Socket;
 /** Opaque reference for a set of server and socket handles */
 typedef struct sHandleSet* HandleSet;
 
+/** State of an asynchronous connect */
+typedef enum
+{
+    SOCKET_STATE_CONNECTING = 0,
+    SOCKET_STATE_FAILED = 1,
+    SOCKET_STATE_CONNECTED = 2
+} SocketState;
+
+
 /**
  * \brief Create a new connection handle set (HandleSet)
  *
@@ -224,6 +233,12 @@ Socket_setConnectTimeout(Socket self, uint32_t timeoutInMs);
 bool
 Socket_connect(Socket self, const char* address, int port);
 
+bool
+Socket_connectAsync(Socket self, const char* address, int port);
+
+SocketState
+Socket_checkAsyncConnectState(Socket self);
+
 /**
  * \brief read from socket to local buffer (non-blocking)
  *
diff --git a/hal/socket/linux/socket_linux.c b/hal/socket/linux/socket_linux.c
index 69fca6a6..1c0883a6 100644
--- a/hal/socket/linux/socket_linux.c
+++ b/hal/socket/linux/socket_linux.c
@@ -298,9 +298,8 @@ Socket_setConnectTimeout(Socket self, uint32_t timeoutInMs)
     self->connectTimeout = timeoutInMs;
 }
 
-
 bool
-Socket_connect(Socket self, const char* address, int port)
+Socket_connectAsync(Socket self, const char* address, int port)
 {
     struct sockaddr_in serverAddress;
 
@@ -312,38 +311,96 @@ Socket_connect(Socket self, const char* address, int port)
 
     self->fd = socket(AF_INET, SOCK_STREAM, 0);
 
-    fd_set fdSet;
-    FD_ZERO(&fdSet);
-    FD_SET(self->fd, &fdSet);
-
     activateTcpNoDelay(self);
 
+#if (CONFIG_ACTIVATE_TCP_KEEPALIVE == 1)
+    activateKeepAlive(self->fd);
+#endif
+
     fcntl(self->fd, F_SETFL, O_NONBLOCK);
 
     if (connect(self->fd, (struct sockaddr *) &serverAddress, sizeof(serverAddress)) < 0) {
-        if (errno != EINPROGRESS)
+
+        if (errno != EINPROGRESS) {
+            self->fd = -1;
             return false;
+        }
     }
 
+    return true; /* is connecting or already connected */
+}
+
+SocketState
+Socket_checkAsyncConnectState(Socket self)
+{
+    struct timeval timeout;
+    timeout.tv_sec = 0;
+    timeout.tv_usec = 0;
+
+    fd_set fdSet;
+    FD_ZERO(&fdSet);
+    FD_SET(self->fd, &fdSet);
+
+    int selectVal = select(self->fd + 1, NULL, &fdSet , NULL, &timeout);
+
+    if (selectVal == 1) {
+
+        /* Check if connection is established */
+
+        int so_error;
+        socklen_t len = sizeof so_error;
+
+        if (getsockopt(self->fd, SOL_SOCKET, SO_ERROR, &so_error, &len) >= 0) {
+
+            if (so_error == 0)
+                return SOCKET_STATE_CONNECTED;
+        }
+
+        return SOCKET_STATE_FAILED;
+    }
+    else if (selectVal == 0) {
+        return SOCKET_STATE_CONNECTING;
+    }
+    else {
+        return SOCKET_STATE_FAILED;
+    }
+}
+
+bool
+Socket_connect(Socket self, const char* address, int port)
+{
+    if (Socket_connectAsync(self, address, port) == false)
+        return false;
+
     struct timeval timeout;
     timeout.tv_sec = self->connectTimeout / 1000;
     timeout.tv_usec = (self->connectTimeout % 1000) * 1000;
 
+    fd_set fdSet;
+    FD_ZERO(&fdSet);
+    FD_SET(self->fd, &fdSet);
+
     if (select(self->fd + 1, NULL, &fdSet , NULL, &timeout) == 1) {
+
+        /* Check if connection is established */
+
         int so_error;
         socklen_t len = sizeof so_error;
 
-        getsockopt(self->fd, SOL_SOCKET, SO_ERROR, &so_error, &len);
+        if (getsockopt(self->fd, SOL_SOCKET, SO_ERROR, &so_error, &len) >= 0) {
 
-        if (so_error == 0)
-            return true;
+            if (so_error == 0)
+                return true;
+        }
     }
 
     close (self->fd);
+    self->fd = -1;
 
     return false;
 }
 
+
 char*
 Socket_getPeerAddress(Socket self)
 {
diff --git a/hal/socket/win32/socket_win32.c b/hal/socket/win32/socket_win32.c
index c686ddc7..75c4f653 100644
--- a/hal/socket/win32/socket_win32.c
+++ b/hal/socket/win32/socket_win32.c
@@ -319,6 +319,81 @@ Socket_setConnectTimeout(Socket self, uint32_t timeoutInMs)
     self->connectTimeout = timeoutInMs;
 }
 
+bool
+Socket_connectAsync(Socket self, const char* address, int port)
+{
+    if (DEBUG_SOCKET)
+        printf("Socket_connect: %s:%i\n", address, port);
+
+    struct sockaddr_in serverAddress;
+    WSADATA wsa;
+    int ec;
+
+    if ((ec = WSAStartup(MAKEWORD(2,0), &wsa)) != 0) {
+        if (DEBUG_SOCKET)
+            printf("WIN32_SOCKET: winsock error: code %i\n", ec);
+        return false;
+    }
+
+
+
+    if (!prepareServerAddress(address, port, &serverAddress))
+        return false;
+
+    self->fd = socket(AF_INET, SOCK_STREAM, 0);
+
+#if CONFIG_ACTIVATE_TCP_KEEPALIVE == 1
+    activateKeepAlive(self->fd);
+#endif
+
+    setSocketNonBlocking(self);
+
+    if (connect(self->fd, (struct sockaddr *) &serverAddress, sizeof(serverAddress)) == SOCKET_ERROR) {
+        if (WSAGetLastError() != WSAEWOULDBLOCK) {
+            self->fd = INVALID_SOCKET;
+            return false;
+        }
+    }
+
+    return true; /* is connecting or already connected */
+}
+
+SocketState
+Socket_checkAsyncConnectState(Socket self)
+{
+    struct timeval timeout;
+    timeout.tv_sec = 0;
+    timeout.tv_usec = 0;
+
+    fd_set fdSet;
+    FD_ZERO(&fdSet);
+    FD_SET(self->fd, &fdSet);
+
+    int selectVal = select(self->fd + 1, NULL, &fdSet , NULL, &timeout);
+
+    if (selectVal == 1) {
+
+        /* Check if connection is established */
+
+        int so_error;
+        int len = sizeof so_error;
+
+        if (getsockopt(self->fd, SOL_SOCKET, SO_ERROR, (char*) (&so_error), &len) >= 0) {
+
+            if (so_error == 0)
+                return SOCKET_STATE_CONNECTED;
+        }
+
+        return SOCKET_STATE_FAILED;
+    }
+    else if (selectVal == 0) {
+        return SOCKET_STATE_CONNECTING;
+    }
+    else {
+        return SOCKET_STATE_FAILED;
+    }
+}
+
 bool
 Socket_connect(Socket self, const char* address, int port)
 {
diff --git a/src/mms/iso_client/iso_client_connection.c b/src/mms/iso_client/iso_client_connection.c
index 1cb2d246..53eca945 100644
--- a/src/mms/iso_client/iso_client_connection.c
+++ b/src/mms/iso_client/iso_client_connection.c
@@ -297,10 +297,12 @@ IsoClientConnection_associate(IsoClientConnection self, IsoConnectionParameters
             CONFIG_TCP_KEEPALIVE_INTERVAL,
             CONFIG_TCP_KEEPALIVE_CNT);
 #endif
-
+    // (1) Function blocks
     if (!Socket_connect(self->socket, params->hostname, params->tcpPort))
         goto returnError;
 
+    // (2) Send connection request message
+
     /* COTP (ISO transport) handshake */
     CotpConnection_init(self->cotpConnection, self->socket, self->receiveBuffer, self->cotpReadBuffer, self->cotpWriteBuffer);
 
@@ -331,6 +333,7 @@ IsoClientConnection_associate(IsoClientConnection self, IsoConnectionParameters
 
     uint64_t timeout = Hal_getTimeInMs() + CONFIG_TCP_READ_TIMEOUT_MS;
 
+    // (3) Waiting for response (blocking)
     while (((packetState = CotpConnection_readToTpktBuffer(self->cotpConnection)) == TPKT_WAITING)
         && (Hal_getTimeInMs() < timeout))
     {
@@ -345,6 +348,8 @@ IsoClientConnection_associate(IsoClientConnection self, IsoConnectionParameters
     if (cotpIndication != COTP_CONNECT_INDICATION)
         goto returnError;
 
+    // (4) Send ACSE Initiate request
+
     /* Upper layers handshake */
     struct sBufferChain sAcsePayload;
     BufferChain acsePayload = &sAcsePayload;
@@ -416,6 +421,8 @@ IsoClientConnection_associate(IsoClientConnection self, IsoConnectionParameters
 
     AcseIndication acseIndication;
 
+    // (5) Wait for ACSE initiate response message
+
     acseIndication = AcseConnection_parseMessage(&(self->acseConnection), &self->presentation->nextPayload);
 
     if (acseIndication != ACSE_ASSOCIATE) {