diff --git a/lib/modem.js b/lib/modem.js
index 23416da..a05c557 100644
--- a/lib/modem.js
+++ b/lib/modem.js
@@ -43,8 +43,10 @@ const modemInfo = {
 let lastTs = new Date();
 
 const port = new SerialPort(config.modem.device, { baudRate: 115200 }, (err) => {
-    logger.warn(`${err.toString()}. Terminating.`);
-    process.exit(1);
+    if (err) {
+        logger.warn(`Error opening modem. ${err}. Terminating.`);
+        process.exit(1);
+    }
 });
 
 
@@ -226,6 +228,10 @@ function readIMSI() {
                     logger.info(`MSISDN: ${modemInfo.msisdn}`);
                 }
             }
+            else {
+                logger.warn('IMSI not detected. Please insert a sim card to your modem.');
+                process.exit(2);
+            }
             resolve(result);
         });
     });