diff --git a/examples/MqttClient/MqttClient.ino b/examples/MqttClient/MqttClient.ino
index 12649b7..1e269d8 100644
--- a/examples/MqttClient/MqttClient.ino
+++ b/examples/MqttClient/MqttClient.ino
@@ -73,8 +73,8 @@
 //#define TINY_GSM_YIELD() { delay(2); }
 
 // Define how you're planning to connect to the internet
-#define TINY_GSM_USE_GPRS false
-#define TINY_GSM_USE_WIFI true
+#define TINY_GSM_USE_GPRS true
+#define TINY_GSM_USE_WIFI false
 
 // set GSM PIN, if any
 #define GSM_PIN ""
diff --git a/src/TinyGsmClientESP8266.h b/src/TinyGsmClientESP8266.h
index c44c221..f701e8d 100644
--- a/src/TinyGsmClientESP8266.h
+++ b/src/TinyGsmClientESP8266.h
@@ -156,7 +156,7 @@ public:
     if (!testAT()) {
       return false;
     }
-    if (pin != NULL) {
+    if (pin && strlen(pin) > 0) {
       DBG("ESP8266 modules do not use an unlock pin!");
     }
     sendAT(GF("E0"));   // Echo Off
diff --git a/src/TinyGsmClientXBee.h b/src/TinyGsmClientXBee.h
index 519c04f..4d4eaa9 100644
--- a/src/TinyGsmClientXBee.h
+++ b/src/TinyGsmClientXBee.h
@@ -305,7 +305,7 @@ public:
       digitalWrite(resetPin, HIGH);
     }
 
-    if (pin != NULL) {
+    if (pin && strlen(pin) > 0) {
       DBG("XBee's do not support SIMs that require an unlock pin!");
     }
 
@@ -528,7 +528,7 @@ public:
    */
 
   bool simUnlock(const char *pin) {  // Not supported
-    if (pin != NULL) {
+    if (pin && strlen(pin) > 0) {
       DBG("XBee's do not support SIMs that require an unlock pin!");
     }
     return false;
@@ -687,7 +687,7 @@ public:
     //nh For no pwd don't set setscurity or pwd
     if (ssid == NULL) retVal = false;;
 
-    if (pwd != NULL)
+    if (pwd && strlen(pwd) > 0)
     {
       sendAT(GF("EE"), 2);  // Set security to WPA2
       if (waitResponse() != 1) retVal = false;
@@ -743,10 +743,10 @@ public:
 
   bool gprsConnect(const char* apn, const char* user = NULL,
                    const char* pwd = NULL) {
-    if (user != NULL) {
+    if (user && strlen(user) > 0) {
       DBG("XBee's do not support SIMs that a user name/password!");
     }
-    if (pwd != NULL) {
+    if (pwd && strlen(pwd) > 0) {
       DBG("XBee's do not support SIMs that a user name/password!");
     }
     XBEE_COMMAND_START_DECORATOR(5, false)
diff --git a/src/TinyGsmCommon.h b/src/TinyGsmCommon.h
index 44c506e..ba3b43e 100644
--- a/src/TinyGsmCommon.h
+++ b/src/TinyGsmCommon.h
@@ -490,9 +490,12 @@ String TinyGsmDecodeHex16bit(String &instr) {
 
 // Unlocks a sim via the 3GPP TS command AT+CPIN
 #define TINY_GSM_MODEM_SIM_UNLOCK_CPIN() \
-  bool simUnlock(const char *pin) { \
-    sendAT(GF("+CPIN=\""), pin, GF("\"")); \
-    return waitResponse() == 1; \
+  bool simUnlock(const char *pin) {      \
+    if (pin && strlen(pin) > 0) { \
+      sendAT(GF("+CPIN=\""), pin, GF("\"")); \
+      return waitResponse() == 1; \
+    } \
+    return true; \
   }