Problem using Http result to make a phone call

Hello everyone
I have been on this code for like weeks now and its giving sleepless night, here is how far i could get it to work, am hook here. please i really need your help now.
I am using SIM900 and Arduino uno
I have been trying to see if I could remedy the situation but to no avail.
I only have knowledge for PHP and MYSQL and am new in C, don't know much in C
The code below can send information to a database and call it back using MySQL and PHP, INSERT and SELECT statement.
I will like to make a phone call with the number returned from the request.
I want to parse the result and make a call to it.
Sorry for the code is long, please have patient with me and read it, if you have a shorter code that can do the same thing, please help me with it. thank you very much.

#include <SoftwareSerial.h>
SoftwareSerial GSM(2, 3); // RX, TX

enum _parseState {
  PS_DETECT_MSG_TYPE,

  PS_IGNORING_COMMAND_ECHO,

  PS_HTTPACTION_TYPE,
  PS_HTTPACTION_RESULT,
  PS_HTTPACTION_LENGTH,

  PS_HTTPREAD_LENGTH,
  PS_HTTPREAD_CONTENT,
  PS_HTTPTERM,
  PS_MAKECALL
};

byte parseState = PS_DETECT_MSG_TYPE;
char buffer[80];
byte pos = 0;

int contentLength = 0;
void resetBuffer() {
  memset(buffer, 0, sizeof(buffer));
  pos = 0;
}

void sendGSM(String msg, int waitMs = 500) {
  GSM.println(msg);
  delay(waitMs);
  while(GSM.available()) {
    parseATText(GSM.read());
  }
}

void setup()
{

  GSM.begin(2400);
  Serial.begin(9600);
  sendGSM("AT+SAPBR=3,1,\"Contype\",\"GPRS\""); 
  sendGSM("AT+SAPBR=3,1,\"APN\",\"9mobile\""); 
                                                //sendGSM("AT+SAPBR=3,1,\"USER\",\"FLAT\""); 
                                                 //sendGSM("AT+SAPBR=3,1,\"PWD\",\"FLAT\"");
  sendGSM("AT+SAPBR=1,1",3000);
  sendGSM("AT+SAPBR=2,1");
  sendGSM("AT+HTTPINIT");  
  sendGSM("AT+CGATT?");
  sendGSM("AT+HTTPPARA=\"CID\",1");
  sendGSM("AT+HTTPPARA=\"URL\",\"ourhelperlinks.com/webservice/data.php?network_id=4&senderNo=2348064996077&recMsg=ItHasWorkedWellNow&timeArrived=10/03/2017\"");
  sendGSM("AT+HTTPACTION=0");
  sendGSM("AT+HTTPTERM");
  sendGSM("AT+SAPBR=0,1");
  sendGSM("AT+CMGF=1");


void loop()
{  
  while(GSM.available()) {
    parseATText(GSM.read());
  }
}

void parseATText(char b) {

  buffer[pos++] = b;

  if ( pos >= sizeof(buffer) )
    resetBuffer();  // just to be safe

  switch (parseState) {
  case PS_DETECT_MSG_TYPE: 
    {
      if ( b == '\n' )
        resetBuffer();
      else {        
        if ( pos == 3 && strcmp(buffer, "AT+") == 0 ) {
          parseState = PS_IGNORING_COMMAND_ECHO;
        }
          if (pos == 1 && strcmp(buffer, "AT+") == 0 ) {
            //Serial.println("Sms Mode Activated");            
            parseState = PS_IGNORING_COMMAND_ECHO;
          }
          if ( strcmp(buffer, "+CMGF") == 1 ) {
            Serial.println("Sms Mode Activated");            
            parseState = PS_MAKECALL;
          }
        else if ( b == ':' ) {

          if ( strcmp(buffer, "+HTTPACTION:") == 0 ) {
            Serial.println("Received HTTPACTION");
            parseState = PS_HTTPACTION_TYPE;
          }
          else if ( strcmp(buffer, "+HTTPREAD:") == 0 ) {
            Serial.println("Received HTTPREAD");            
            parseState = PS_HTTPREAD_LENGTH;
          }
         
          resetBuffer();
        }
      }
    }
    break;

  case PS_IGNORING_COMMAND_ECHO:
    {
      if ( b == '\n' ) {
        Serial.print("Ignoring echo: ");
        Serial.println(buffer);
        parseState = PS_DETECT_MSG_TYPE;
        resetBuffer();
      }
    }
    break;

  case PS_HTTPACTION_TYPE:
    {
      if ( b == ',' ) {
        Serial.print("HTTPACTION type is ");
        Serial.println(buffer);
        parseState = PS_HTTPACTION_RESULT;
        resetBuffer();
      }
    }
    break;

  case PS_HTTPACTION_RESULT:
    {
      if ( b == ',' ) {
        Serial.print("HTTPACTION result is ");
        Serial.println(buffer);
        parseState = PS_HTTPACTION_LENGTH;
        resetBuffer();
      }
    }
    break;

  case PS_HTTPACTION_LENGTH:
    {
      if ( b == '\n' ) {
        Serial.print("HTTPACTION length is ");
        Serial.println(buffer);
        
        // now request content
        GSM.print("AT+HTTPREAD=0,");
        GSM.println(buffer);
        
        parseState = PS_DETECT_MSG_TYPE;
        resetBuffer();
      }
    }
    break;

  case PS_HTTPREAD_LENGTH:
    {
      if ( b == '\n' ) {
        contentLength = atoi(buffer);
        Serial.print("HTTPREAD length is ");
        Serial.println(contentLength);
        
        Serial.print("HTTPREAD content: ");
        
        parseState = PS_HTTPTERM;
        
        resetBuffer();
      }
    }
    break;

     case PS_MAKECALL:
    {
     if ( b == '\n' ) {
          sendGSM("ATD+" b ";");                   
         //now request content
     GSM.println("ATD +2348064996077;");
        
        delay(20000);
        GSM.println(buffer);
        
        parseState = PS_DETECT_MSG_TYPE;
        resetBuffer();
      } 
    }
    break;

                                        
  }
}

Am trying to upload the sketch but its telling me

Expression cannot be used as a function
(byte b)
in sendGSM("ATD+" b ";");

I want to parse the result and make a call to it.
If i put a number instead of the variable num, the phone call goes but not going with the variable, and i want it to make a call to the number gotten from the database

I made the SELECT statement returns only the number which I intend to call. But I dont know how place that final call from the Arduino sketch.
I hope you understand my issue, i will really appreciate your help cos this code has given me sleepless night for more than a week. thanks for understanding.
Please don't read my message and pass, please help me even if its just an idea. thanks
I will appreciate your help and swift response.
Thank you.

Hello everyone
i have been able to strcpy the result to a variable, i null terminated it and tried to make a call to the variable but the call is not going through, here is the code

if ( contentLength <= 0 ) {
         char num [32];
        strcpy(num, buffer);
        buffer[ pos ] = 0;
        Serial.println(num);
       sendGSM("AT+CMGF=1");// changing to sms mode
       delay(2000);
      char n=sprintf( buffer, "ATD+%s;", num );
      printf("%s\n", n);
       delay(20000);
        resetBuffer();

Here is the result i got in the serial monitor

Ignoring echo: AT+SAPBR=3,1,"Contype","GPRS" 
Ignoring echo: AT+SAPBR=3,1,"APN","APN" 
Ignoring echo: AT+SAPBR=3,1,"USER","FLAT" 
Ignoring echo: AT+SAPBR=3,1,"PWD","FLAT"
Ignoring echo: AT+SAPBR=1,1 
Ignoring echo: AT+SAPBR=2,1 
Ignoring echo: AT+HTTPINIT 
Ignoring echo: AT+HTTPSSL=1 
Ignoring echo: AT+CGATT? 
Ignoring echo: AT+HTTPPARA="CID",1 
Ignoring echo: Received HTTPACTION 
HTTPACTION type is 0, 
HTTPACTION result is 200, 
HTTPACTION length is 12 
Ignoring echo: AT+HTTPREAD=0,12 
Received HTTPREAD 
HTTPREAD length is 12 
HTTPREAD content: 91xxxxxxxxxx 
OK
91xxxxxxxxxx 
OK

Its show okay but the call doesn't go
Any help or idea will be appreciated, thanks.