How to send to multiple recipients in sim800?

I've been using this code but it only sends to the first number. The second number does not receive any.

void setup() {
//Begin serial comunication with Arduino and Arduino IDE (Serial Monitor)
Serial.begin(9600);
while(!Serial);

//Being serial communication witj Arduino and SIM800
serialSIM800.begin(9600);
delay(1000);

Serial.println("Setup Complete!");
Serial.println("Sending SMS...");

//Set SMS format to ASCII
serialSIM800.write("AT+CMGF=1\r\n");
delay(1000);

//Send new SMS command and message number
serialSIM800.write("AT+CMGS="+63947517xxxx"\r\n");
serialSIM800.write("AT+CMGS="+63998950xxxx"\r\n");
delay(1000);

//Send SMS content
serialSIM800.write("Multiple recipient test. Dont reply bes.\n\n Sent From GSM");
delay(1000);

//Send Ctrl+Z / ESC to denote SMS message is complete
serialSIM800.write((char)26);
delay(1000);

Serial.println("SMS Sent!");
}

void loop() {
}

Why would you expect it to anything different?

Make a list of the steps that you need to take to send the message to one recipient. Multiply that by the number of recipients to get the number of steps needed to send the message to all recipients.

How many steps do you have?