2G Network in Haiti - not connecting to GPRS

I have a Sim900 using a Hologram SIM that connects just fine in France. When I’ve taken this Sim900 to Haiti, I can see that it connects to the cell tower (GSM), more specifically Digicel (Jamaica). That is this function boolean connectGsmNetwork() returns true. But it fails to connect to the GPRS network in the script below. That is, this function boolean connectGsmNetwork() returns false. Is this the expected behavior in Haiti, i.e. no 2G connection to GPRS as opposed to France where this works fine?

// Select your modem:

#include <TinyGsmClient.h>
#include <ArduinoHttpClient.h>
//include some libraries
//#include <ArduinoJson.h>

// Set serial for debug console (to the Serial Monitor, default speed 115200)
#define SerialMon Serial

// Import paswword and other stuff
//#include "arduino_secrets.h"
#include <SoftwareSerial.h>
SoftwareSerial SerialAT(7, 8);  // RX, TX

// Increase RX buffer to capture the entire response
// Chips without internal buffering (A6/A7, ESP8266, M590)
// need enough space in the buffer for the entire response
// else data will be lost (and the http library will fail).
#if !defined(TINY_GSM_RX_BUFFER)
#define TINY_GSM_RX_BUFFER 650

// See all AT commands, if wanted

// Define the serial console for debug prints, if needed
#define TINY_GSM_DEBUG SerialMon

// set GSM PIN, if any
#define GSM_PIN ""

// Your GPRS credentials, if any
const char apn[]      = "hologram";
const char gprsUser[] = "";
const char gprsPass[] = "";

const char server[]   = "your.restapi.com"; //REST_SERVER;
const char resource[] = "/your/resource/";
const char path[]   = "/api/endpoint/";// REST_ENDPOINT;

String imei_string = "";

#include <StreamDebugger.h>
StreamDebugger debugger(SerialAT, SerialMon);

// GSM connection
TinyGsm modem = TinyGsm(debugger);
TinyGsm modem = TinyGsm(SerialAT);

// Socket connection
#ifdef USE_SSL
TinyGsmClientSecure socket = TinyGsmClientSecure(modem);
const int           port   = 443;
TinyGsmClient socket = TinyGsmClient(modem);
const int     port   = 80;

boolean gprsOpen = false;
boolean sockOpen = false;
boolean postOK = false;
int attempt = 1; //compteur de tentative

void setup() {
  // Set console baud rate
  SerialMon.println("Switching on...");

// Added to the script

  // !!!!!!!!!!!
  // Set your reset, enable, power pins here
  // !!!!!!!!!!!

  // Set GSM module baud rate

boolean isValidNumber(String str) {
  for(byte i=0;i<str.length();i++) {
    if(!isDigit(str.charAt(i))) return false;
  return true;

boolean restartAndConnect() {
  // Restart takes quite some time
  // To skip it, call init() instead of restart()
  SerialMon.println("Initializing modem...");
  // modem.init();

  String modemInfo = modem.getModemInfo();
  SerialMon.print("Modem Info: ");

  if (imei_string.length() == 0) {
    imei_string = modem.getIMEI();

    /* Test
    SerialMon.print(F("imei_string: "));
    imei_string = "1234?abc";
    SerialMon.print(F("imei_string: "));

    // Sometimes modem.getIMEI() returns garbage, so checking it here
    while(!isValidNumber(imei_string)) {
        //SerialMon.print(F("imei_string: "));
        imei_string = modem.getIMEI();
        //SerialMon.print(F("imei_string: "));

if (GSM_PIN && modem.getSimStatus() != 3) { modem.simUnlock(GSM_PIN); }

  if (!connectSocket()) { 
    return false; // failed to connect socket
  return true;

void loop() {
  if (restartAndConnect()) { httpPost(); }
  if (postOK==true) { attempt = 1; postOK = false;  delay(3600000); } // attente 1 hr 
    else { 
      SerialMon.println("failure of attempt " + attempt);
      attempt = attempt + 1; 
      delay(25000); } //attente 30s  si problème
//  waitSecondsAndSayIt(1 * 60);

void waitSecondsAndSayIt(int s) {
  Serial.println("Wait " + String(s) + " seconds");
  delay(s * 1000);

boolean connectGsmNetwork() {
  SerialMon.print("Waiting for GSM network...");
  boolean connected = modem.waitForNetwork() && modem.isNetworkConnected();
  if (connected) { 
    SerialMon.println("GSM network connected"); 
  else {
    SerialMon.println(" failed connecting GSM.");
  return connected;

boolean connectGprs() {
  if (!connectGsmNetwork()) {
    return false;

  SerialMon.println("Connecting GPRS...");
  // GPRS connection parameters are usually set after network registration
  SerialMon.print(F("Connecting to "));
  boolean connected = modem.gprsConnect(apn, gprsUser, gprsPass) && modem.isGprsConnected();
  if (connected) { 
    gprsOpen = true;
    SerialMon.println(" - GPRS connected"); 
  else {
    SerialMon.println("  - failed connecting GPRS.");
  return connected;

boolean connectSocket() {
  if (!connectGprs()) {
    return false;
  SerialMon.print("Connecting socket...");
  SerialMon.print("Connecting to ");
  boolean connected = socket.connect(server, port);
  if (connected) { 
    sockOpen = true;
    SerialMon.println("socket connected!"); 
  else {
    SerialMon.println("socket connection failed!");
  return connected;

void networkDisconnect() {
  if (sockOpen) {
    sockOpen = false;
    // Shutdown
    SerialMon.println(F("Server disconnected"));

  if (gprsOpen) {
    gprsOpen = false;

    SerialMon.println(F("GPRS disconnected"));

void httpGet() {
  // previously
  //if (!socket.connect(server, port)) {

  // Make a HTTP GET request:
  SerialMon.println("Performing HTTP GET request...");

  // writing request
  socket.print(String("GET ") + resource + " HTTP/1.1\r\n");
  socket.print(String("Host: ") + server + "\r\n");
  socket.print("Connection: close\r\n\r\n");
  // getting response
1 Like

Try to put some delay between gprs connection commands.
Start with five seconds ,time to settle the command and receive the answer from gsm tower. When you get the connection, decrease the delay .

okay, stay tuned …thanks

I wish you all the best and I am looking forward to your response.

I asked Hologram if they had any customers in Haiti that could validate whether or not their SIM would work with either Natcom or Digicel.

Unfortunately, I have wasted a lot of time and resources trying to setup LTE Cameras that do list Natcom/Haiti as supported carriers:

I am working on a new project for Haiti that will require a Raspberry Pi GSM/GPRS/GNSS Bluetooth HAT Expansion Board.

I am selfishly hoping and praying that you make it work. :slight_smile:

I am working through some AT command diagnostics with support.hologram.io, but I don’t have access to the Haiti Sim900 once I sent it to Haiti from France, so it will be awhile until I get a VNC connection there to run AT diagnositics.

But, I can tell you this, we have Hologram Sim working there on 3G that worked first time. It is this sketch: MKR GSM 1400 3G with Hologram Sim

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