diff --git a/src/modem.rs b/src/modem.rs
index 87f908b..a8e82a8 100644
--- a/src/modem.rs
+++ b/src/modem.rs
@@ -102,8 +102,13 @@ impl<UART: serial::Uart> Modem<UART> {
         pwrkey.set_low().map_err(|_| ModemError::SetupError("Error setting PWRKEY to low.".to_string()))?;
         thread::sleep(Duration::from_millis(1000));
         pwrkey.set_high().map_err(|_| ModemError::SetupError("Error setting PWRKEY to high.".to_string()))?;
-        println!("Waiting 3s for sim module to come online ...");
-        thread::sleep(Duration::from_millis(3000));
+        println!("Waiting for sim module to come online ...");
+        loop {
+            match self.send_command(Command::probe()) {
+                Ok(_) => break,
+                _ => continue,
+            }
+        }
         Ok(())
     }