Fixed bad reference and added not implemented

src/TinyGsmClientA6.h

@@ -190,6 +190,8 @@ class TinyGsmA6 : public TinyGsmModem<TinyGsmA6>,
 
   bool sleepEnableImpl(bool enable = true) TINY_GSM_ATTR_NOT_AVAILABLE;
 
+  bool setPhoneFunctionalityImpl(uint8_t fun, bool reset = false) TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
   /*
    * Generic network functions
    */

src/TinyGsmClientESP8266.h

@@ -200,6 +200,8 @@ class TinyGsmESP8266 : public TinyGsmModem<TinyGsmESP8266>,
 
   bool sleepEnableImpl(bool enable = true) TINY_GSM_ATTR_NOT_AVAILABLE;
 
+  bool setPhoneFunctionalityImpl(uint8_t fun, bool reset = false) TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
   /*
    * Generic network functions
    */

src/TinyGsmClientM95.h

@@ -226,6 +226,8 @@ class TinyGsmM95 : public TinyGsmModem<TinyGsmM95>,
     return waitResponse() == 1;
   }
 
+  bool setPhoneFunctionalityImpl(uint8_t fun, bool reset = false) TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
   /*
    * Generic network functions
    */

src/TinyGsmClientSequansMonarch.h

@@ -315,6 +315,8 @@ class TinyGsmSequansMonarch
     return waitResponse() == 1;
   }
 
+  bool setPhoneFunctionality(uint8_t fun, bool reset = false) TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
   /*
    * Generic network functions
    */

src/TinyGsmClientXBee.h

@@ -572,6 +572,8 @@ class TinyGsmXBee : public TinyGsmModem<TinyGsmXBee>,
 
   bool sleepEnableImpl(bool enable = true) TINY_GSM_ATTR_NOT_IMPLEMENTED;
 
+  bool setPhoneFunctionalityImpl(uint8_t fun, bool reset = false) TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
   /*
    * Generic network functions
    */

src/TinyGsmModem.tpp

@@ -66,7 +66,7 @@ class TinyGsmModem {
     return thisModem().sleepEnableImpl(enable);
   }
   bool setPhoneFunctionality(uint8_t fun, bool reset = false) {
-    return thisModem().setPhoneFunctionality(fun, reset);
+    return thisModem().setPhoneFunctionalityImpl(fun, reset);
   }
 
   /*
@@ -174,6 +174,8 @@ class TinyGsmModem {
 
   bool sleepEnableImpl(bool enable = true) TINY_GSM_ATTR_NOT_IMPLEMENTED;
 
+  bool setPhoneFunctionalityImpl(uint8_t fun, bool reset = false) TINY_GSM_ATTR_NOT_IMPLEMENTED;
+
   /*
    * Generic network functions
    */