diff --git a/src/TinyGsmClientA6.h b/src/TinyGsmClientA6.h
index 414b8d8..a53890b 100644
--- a/src/TinyGsmClientA6.h
+++ b/src/TinyGsmClientA6.h
@@ -66,6 +66,7 @@ public:
 
 public:
   virtual int connect(const char *host, uint16_t port) {
+    stop();
     TINY_GSM_YIELD();
     rx.clear();
     uint8_t newMux = -1;
@@ -94,6 +95,7 @@ public:
     at->sendAT(GF("+CIPCLOSE="), mux);
     sock_connected = false;
     at->waitResponse();
+    rx.clear();
   }
 
   virtual size_t write(const uint8_t *buf, size_t size) {
@@ -216,9 +218,7 @@ public:
   }
 
   void maintain() {
-    //while (stream.available()) {
-      waitResponse(10, NULL, NULL);
-    //}
+    waitResponse(10, NULL, NULL);
   }
 
   bool factoryDefault() {
@@ -240,6 +240,10 @@ public:
     return res;
   }
 
+  bool hasSSL() {
+    return false;
+  }
+
   /*
    * Power functions
    */
@@ -400,8 +404,10 @@ public:
   }
 
   bool gprsDisconnect() {
+    // Shut the TCP/IP connection
     sendAT(GF("+CIPSHUT"));
-    waitResponse(5000L);
+    if (waitResponse(60000L) != 1)
+      return false;
 
     for (int i = 0; i<3; i++) {
       sendAT(GF("+CGATT=0"));
@@ -612,12 +618,12 @@ protected:
   int modemSend(const void* buff, size_t len, uint8_t mux) {
     sendAT(GF("+CIPSEND="), mux, ',', len);
     if (waitResponse(2000L, GF(GSM_NL ">")) != 1) {
-      return -1;
+      return 0;
     }
     stream.write((uint8_t*)buff, len);
     stream.flush();
     if (waitResponse(10000L, GFP(GSM_OK), GF(GSM_NL "FAIL")) != 1) {
-      return -1;
+      return 0;
     }
     return len;
   }
diff --git a/src/TinyGsmClientESP8266.h b/src/TinyGsmClientESP8266.h
index 1ded3ca..44ed149 100644
--- a/src/TinyGsmClientESP8266.h
+++ b/src/TinyGsmClientESP8266.h
@@ -53,6 +53,7 @@ public:
 
 public:
   virtual int connect(const char *host, uint16_t port) {
+    stop();
     TINY_GSM_YIELD();
     rx.clear();
     sock_connected = at->modemConnect(host, port, mux);
@@ -76,6 +77,7 @@ public:
     at->sendAT(GF("+CIPCLOSE="), mux);
     sock_connected = false;
     at->waitResponse();
+    rx.clear();
   }
 
   virtual size_t write(const uint8_t *buf, size_t size) {
@@ -159,6 +161,7 @@ public:
 
 public:
   virtual int connect(const char *host, uint16_t port) {
+    stop();
     TINY_GSM_YIELD();
     rx.clear();
     sock_connected = at->modemConnect(host, port, mux, true);
@@ -209,7 +212,7 @@ public:
   }
 
   void maintain() {
-      waitResponse(10, NULL, NULL);
+    waitResponse(10, NULL, NULL);
   }
 
   bool factoryDefault() {
@@ -370,12 +373,12 @@ protected:
   int modemSend(const void* buff, size_t len, uint8_t mux) {
     sendAT(GF("+CIPSEND="), mux, ',', len);
     if (waitResponse(GF(">")) != 1) {
-      return -1;
+      return 0;
     }
     stream.write((uint8_t*)buff, len);
     stream.flush();
     if (waitResponse(10000L, GF(GSM_NL "SEND OK" GSM_NL)) != 1) {
-      return -1;
+      return 0;
     }
     return len;
   }
diff --git a/src/TinyGsmClientM590.h b/src/TinyGsmClientM590.h
index 57a6195..21539ae 100644
--- a/src/TinyGsmClientM590.h
+++ b/src/TinyGsmClientM590.h
@@ -68,6 +68,7 @@ public:
 
 public:
   virtual int connect(const char *host, uint16_t port) {
+    stop();
     TINY_GSM_YIELD();
     rx.clear();
     sock_connected = at->modemConnect(host, port, mux);
@@ -91,6 +92,7 @@ public:
     at->sendAT(GF("+TCPCLOSE="), mux);
     sock_connected = false;
     at->waitResponse();
+    rx.clear();
   }
 
   virtual size_t write(const uint8_t *buf, size_t size) {
@@ -242,6 +244,10 @@ public:
     return res;
   }
 
+  bool hasSSL() {
+    return false;
+  }
+
   /*
    * Power functions
    */
diff --git a/src/TinyGsmClientSIM800.h b/src/TinyGsmClientSIM800.h
index 8da1acb..6490842 100644
--- a/src/TinyGsmClientSIM800.h
+++ b/src/TinyGsmClientSIM800.h
@@ -535,7 +535,8 @@ public:
   }
 
   bool gprsDisconnect() {
-    sendAT(GF("+CIPSHUT"));  // Shut the TCP/IP connection
+    // Shut the TCP/IP connection
+    sendAT(GF("+CIPSHUT"));
     if (waitResponse(60000L) != 1)
       return false;
 
@@ -770,12 +771,12 @@ protected:
   int modemSend(const void* buff, size_t len, uint8_t mux) {
     sendAT(GF("+CIPSEND="), mux, ',', len);
     if (waitResponse(GF(">")) != 1) {
-      return -1;
+      return 0;
     }
     stream.write((uint8_t*)buff, len);
     stream.flush();
     if (waitResponse(GF(GSM_NL "DATA ACCEPT:")) != 1) {
-      return -1;
+      return 0;
     }
     streamSkipUntil(','); // Skip mux
     return stream.readStringUntil('\n').toInt();
diff --git a/src/TinyGsmClientU201.h b/src/TinyGsmClientU201.h
index 051598c..4466058 100644
--- a/src/TinyGsmClientU201.h
+++ b/src/TinyGsmClientU201.h
@@ -68,6 +68,7 @@ public:
 
 public:
   virtual int connect(const char *host, uint16_t port) {
+    stop();
     TINY_GSM_YIELD();
     rx.clear();
     sock_connected = at->modemConnect(host, port, &mux);
@@ -92,6 +93,7 @@ public:
     at->sendAT(GF("+USOCL="), mux);
     sock_connected = false;
     at->waitResponse();
+    rx.clear();
   }
 
   virtual size_t write(const uint8_t *buf, size_t size) {
@@ -106,7 +108,7 @@ public:
 
   virtual int available() {
     TINY_GSM_YIELD();
-    if (!rx.size() && sock_connected) { // TODO
+    if (!rx.size() && sock_connected) {
       at->maintain();
     }
     return rx.size() + sock_available;
@@ -180,6 +182,7 @@ public:
 
 public:
   virtual int connect(const char *host, uint16_t port) {
+    stop();
     TINY_GSM_YIELD();
     rx.clear();
     sock_connected = at->modemConnect(host, port, &mux, true);
@@ -258,6 +261,12 @@ public:
     return waitResponse() == 1;
   }
 
+  String getModemInfo() TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
+  bool hasSSL() {
+    return true;
+  }
+
   /*
    * Power functions
    */
diff --git a/src/TinyGsmClientXBee.h b/src/TinyGsmClientXBee.h
index f5d296c..87dbcda 100644
--- a/src/TinyGsmClientXBee.h
+++ b/src/TinyGsmClientXBee.h
@@ -9,7 +9,7 @@
 #ifndef TinyGsmClientXBee_h
 #define TinyGsmClientXBee_h
 
-// #define TINY_GSM_DEBUG Serial
+//#define TINY_GSM_DEBUG Serial
 
 #if !defined(TINY_GSM_RX_BUFFER)
   #define TINY_GSM_RX_BUFFER 256
@@ -459,11 +459,7 @@ fail:
    * Messaging functions
    */
 
-  void sendUSSD() {
-  }
-
-  void sendSMS() {
-  }
+  String sendUSSD(const String& code) TINY_GSM_ATTR_NOT_IMPLEMENTED;
 
   bool sendSMS(const String& number, const String& text) {
     commandMode();