diff --git a/src/at_commands.rs b/src/at_commands.rs
index 99359ec..492cde0 100644
--- a/src/at_commands.rs
+++ b/src/at_commands.rs
@@ -226,6 +226,7 @@ impl ATResponseParser {
             self.curr_line = Some(text.to_string());
             Ok(())
         } else {
+            self.curr_line = Some(line);
             Err(ATParseError::InvalidResponse)
         }
     }
@@ -300,10 +301,17 @@ impl ATCommand for ATInformationCommand {
     }
 }
 
+#[derive(Debug)]
+pub enum EnterPinResult {
+    Ok,
+    Error,
+    ErrorMessage(String),
+}
+
 #[derive(Debug, Clone)]
 pub struct EnterPinCommand(pub String);
 impl ATCommand for EnterPinCommand {
-    type Response = String;
+    type Response = EnterPinResult;
 
     fn execute(&self, at_commands: &mut ATCommands) -> Vec<String> {
         at_commands.raw_command(self, format!("AT+CPIN={}", self.0))
@@ -312,17 +320,27 @@ impl ATCommand for EnterPinCommand {
     fn parse_response(parser: &mut ATResponseParser) -> Result<Self::Response, ATParseError> {
         while let Some(line) = parser.readline() {
             if line.starts_with("OK") {
-                return Ok("OK".to_owned());
+                return Ok(EnterPinResult::Ok);
+            } else if line.starts_with("ERROR") {
+                return Ok(EnterPinResult::Error);
+            } else if let Some(status) = line.strip_prefix("+CME ERROR: ") {
+                return Ok(EnterPinResult::ErrorMessage(status.to_string()));
             }
         }
         Err(ATParseError::EOF)
     }
 }
+#[derive(Debug)]
+pub enum CheckPinResult {
+    Ok,
+    Error,
+    ErrorMessage(String),
+}
 
 #[derive(Debug, Clone)]
 pub struct CheckPinCommand;
 impl ATCommand for CheckPinCommand {
-    type Response = String;
+    type Response = CheckPinResult;
 
     fn execute(&self, at_commands: &mut ATCommands) -> Vec<String> {
         at_commands.raw_command(self, "AT+CPIN?".to_string())
@@ -331,13 +349,23 @@ impl ATCommand for CheckPinCommand {
     fn parse_response(parser: &mut ATResponseParser) -> Result<Self::Response, ATParseError> {
         while let Some(line) = parser.readline() {
             if line.starts_with("OK") {
-                return Ok("OK".to_owned());
+                return Ok(CheckPinResult::Ok);
+            } else if line.starts_with("ERROR") {
+                return Ok(CheckPinResult::Error);
+            } else if let Some(status) = line.strip_prefix("+CME ERROR: ") {
+                return Ok(CheckPinResult::ErrorMessage(status.to_string()));
             }
         }
         Err(ATParseError::EOF)
     }
 }
 
+#[derive(Debug)]
+pub enum SelectSMSFormatResult {
+    Ok,
+    Error,
+}
+
 #[derive(Debug, Clone, Copy)]
 pub enum SMSFormat {
     PDUMode = 0,
@@ -347,7 +375,7 @@ pub enum SMSFormat {
 #[derive(Debug, Clone)]
 pub struct SelectSMSFormatCommand(pub SMSFormat);
 impl ATCommand for SelectSMSFormatCommand {
-    type Response = String;
+    type Response = SelectSMSFormatResult;
 
     fn execute(&self, at_commands: &mut ATCommands) -> Vec<String> {
         at_commands.raw_command(self, format!("AT+CMGF={}", self.0 as u8))
@@ -356,7 +384,9 @@ impl ATCommand for SelectSMSFormatCommand {
     fn parse_response(parser: &mut ATResponseParser) -> Result<Self::Response, ATParseError> {
         while let Some(line) = parser.readline() {
             if line.starts_with("OK") {
-                return Ok("OK".to_owned());
+                return Ok(SelectSMSFormatResult::Ok);
+            } else if line.starts_with("ERROR") {
+                return Ok(SelectSMSFormatResult::Error);
             }
         }
         Err(ATParseError::EOF)