diff --git a/lib/biju/at/cme_error.rb b/lib/biju/at/cme_error.rb
new file mode 100644
index 0000000..4647bfa
--- /dev/null
+++ b/lib/biju/at/cme_error.rb
@@ -0,0 +1,73 @@
+module Biju
+  module AT
+    # Message Equipement Failure
+    class CmeError < Error
+      ERRORS = {
+        0 => 'Phone failure',
+        1 => 'No connection to phone',
+        2 => 'Phone adapter link reserved',
+        3 => 'Operation not allowed',
+        4 => 'Operation not supported',
+        5 => 'PH_SIM PIN required',
+        6 => 'PH_FSIM PIN required',
+        7 => 'PH_FSIM PUK required',
+        10 => 'SIM not inserted',
+        11 => 'SIM PIN required',
+        12 => 'SIM PUK required',
+        13 => 'SIM failure',
+        14 => 'SIM busy',
+        15 => 'SIM wrong',
+        16 => 'Incorrect password',
+        17 => 'SIM PIN2 required',
+        18 => 'SIM PUK2 required',
+        20 => 'Memory full',
+        21 => 'Invalid index',
+        22 => 'Not found',
+        23 => 'Memory failure',
+        24 => 'Text string too long',
+        25 => 'Invalid characters in text string',
+        26 => 'Dial string too long',
+        27 => 'Invalid characters in dial string',
+        30 => 'No network service',
+        31 => 'Network timeout',
+        32 => 'Network not allowed, emergency calls only',
+        40 => 'Network personalization PIN required',
+        41 => 'Network personalization PUK required',
+        42 => 'Network subset personalization PIN required',
+        43 => 'Network subset personalization PUK required',
+        44 => 'Service provider personalization PIN required',
+        45 => 'Service provider personalization PUK required',
+        46 => 'Corporate personalization PIN required',
+        47 => 'Corporate personalization PUK required',
+        48 => 'PH-SIM PUK required',
+        100 => 'Unknown error',
+        103 => 'Illegal MS',
+        106 => 'Illegal ME',
+        107 => 'GPRS services not allowed',
+        111 => 'PLMN not allowed',
+        112 => 'Location area not allowed',
+        113 => 'Roaming not allowed in this location area',
+        126 => 'Operation temporary not allowed',
+        132 => 'Service operation not supported',
+        133 => 'Requested service option not subscribed',
+        134 => 'Service option temporary out of order',
+        148 => 'Unspecified GPRS error',
+        149 => 'PDP authentication failure',
+        150 => 'Invalid mobile class',
+        256 => 'Operation temporarily not allowed',
+        257 => 'Call barred',
+        258 => 'Phone is busy',
+        259 => 'User abort',
+        260 => 'Invalid dial string',
+        261 => 'SS not executed',
+        262 => 'SIM Blocked',
+        263 => 'Invalid block',
+        772 => 'SIM powered down',
+      }
+
+      def initialize(id)
+        super(id, 100)
+      end
+    end
+  end
+end
diff --git a/lib/biju/at/cms_error.rb b/lib/biju/at/cms_error.rb
new file mode 100644
index 0000000..a489ab4
--- /dev/null
+++ b/lib/biju/at/cms_error.rb
@@ -0,0 +1,99 @@
+module Biju
+  module AT
+    # Message Service Failure
+    class CmsError < Error
+      ERRORS = {
+        1 => 'Unassigned number',
+        8 => 'Operator determined barring',
+        10 => 'Call bared',
+        21 => 'Short message transfer rejected',
+        27 => 'Destination out of service',
+        28 => 'Unindentified subscriber',
+        29 => 'Facility rejected',
+        30 => 'Unknown subscriber',
+        38 => 'Network out of order',
+        41 => 'Temporary failure',
+        42 => 'Congestion',
+        47 => 'Recources unavailable',
+        50 => 'Requested facility not subscribed',
+        69 => 'Requested facility not implemented',
+        81 => 'Invalid short message transfer reference value',
+        95 => 'Invalid message unspecified',
+        96 => 'Invalid mandatory information',
+        97 => 'Message type non existent or not implemented',
+        98 => 'Message not compatible with short message protocol',
+        99 => 'Information element non-existent or not implemente',
+        111 => 'Protocol error, unspecified',
+        127 => 'Internetworking , unspecified',
+        128 => 'Telematic internetworking not supported',
+        129 => 'Short message type 0 not supported',
+        130 => 'Cannot replace short message',
+        143 => 'Unspecified TP-PID error',
+        144 => 'Data code scheme not supported',
+        145 => 'Message class not supported',
+        159 => 'Unspecified TP-DCS error',
+        160 => 'Command cannot be actioned',
+        161 => 'Command unsupported',
+        175 => 'Unspecified TP-Command error',
+        176 => 'TPDU not supported',
+        192 => 'SC busy',
+        193 => 'No SC subscription',
+        194 => 'SC System failure',
+        195 => 'Invalid SME address',
+        196 => 'Destination SME barred',
+        197 => 'SM Rejected-Duplicate SM',
+        198 => 'TP-VPF not supported',
+        199 => 'TP-VP not supported',
+        208 => 'D0 SIM SMS Storage full',
+        209 => 'No SMS Storage capability in SIM',
+        210 => 'Error in MS',
+        211 => 'Memory capacity exceeded',
+        212 => 'Sim application toolkit busy',
+        213 => 'SIM data download error',
+        255 => 'Unspecified error cause',
+        300 => 'ME Failure',
+        301 => 'SMS service of ME reserved',
+        302 => 'Operation not allowed',
+        303 => 'Operation not supported',
+        304 => 'Invalid PDU mode parameter',
+        305 => 'Invalid Text mode parameter',
+        310 => 'SIM not inserted',
+        311 => 'SIM PIN required',
+        312 => 'PH-SIM PIN required',
+        313 => 'SIM failure',
+        314 => 'SIM busy',
+        315 => 'SIM wrong',
+        316 => 'SIM PUK required',
+        317 => 'SIM PIN2 required',
+        318 => 'SIM PUK2 required',
+        320 => 'Memory failure',
+        321 => 'Invalid memory index',
+        322 => 'Memory full',
+        330 => 'SMSC address unknown',
+        331 => 'No network service',
+        332 => 'Network timeout',
+        340 => 'No +CNMA expected',
+        500 => 'Unknown error',
+        512 => 'User abort',
+        513 => 'Unable to store',
+        514 => 'Invalid Status',
+        515 => 'Device busy or Invalid Character in string',
+        516 => 'Invalid length',
+        517 => 'Invalid character in PDU',
+        518 => 'Invalid parameter',
+        519 => 'Invalid length or character',
+        520 => 'Invalid character in text',
+        521 => 'Timer expired',
+        522 => 'Operation temporary not allowed',
+        532 => 'SIM not ready',
+        534 => 'Cell Broadcast error unknown',
+        535 => 'Protocol stack busy',
+        538 => 'Invalid parameter',
+      }
+
+      def initialize(id)
+        super(id, 500)
+      end
+    end
+  end
+end
diff --git a/lib/biju/at/error.rb b/lib/biju/at/error.rb
new file mode 100644
index 0000000..08b6a70
--- /dev/null
+++ b/lib/biju/at/error.rb
@@ -0,0 +1,17 @@
+module Biju
+  module AT
+    class Error < ::Exception
+      ERRORS = {
+        1 => 'Unknown error',
+      }
+
+      def initialize(id, default = 1)
+        @error_id = (self.class::ERRORS.has_key?(id) ? id : default)
+      end
+
+      def to_s
+        "#{self.class::ERRORS[@error_id]} (#{@error_id})"
+      end
+    end
+  end
+end
diff --git a/lib/biju/hayes.rb b/lib/biju/hayes.rb
index a99e125..6c7589a 100644
--- a/lib/biju/hayes.rb
+++ b/lib/biju/hayes.rb
@@ -1,3 +1,7 @@
+require 'biju/at/error'
+require 'biju/at/cms_error'
+require 'biju/at/cme_error'
+
 module Biju
   class Hayes
     attr_reader :modem
@@ -96,7 +100,16 @@ module Biju
     private
 
     def hayes_to_obj(str)
-      ATTransform.new.apply(ATParser.new.parse(str))
+      res = ATTransform.new.apply(ATParser.new.parse(str))
+
+      case res[:cmd]
+      when "+CMS ERROR"
+        raise AT::CmsError.new(res[:result])
+      when "+CME ERROR"
+        raise AT::CmeError.new(res[:result])
+      end
+
+      res
     end
   end
 end
diff --git a/lib/biju/parser.rb b/lib/biju/parser.rb
index 8ec83b1..41dc547 100644
--- a/lib/biju/parser.rb
+++ b/lib/biju/parser.rb
@@ -17,9 +17,9 @@ module Biju
     # RESPONSE
     rule(:response) { ((status | command) >> crlf) | prompt }
     rule(:prompt) { str('> ').as(:prompt) }
-    rule(:command) { mgl | pms | mgf | mgs | mserror }
+    rule(:command) { mgl | pms | mgf | mgs | merror }
 
-    rule(:mserror) { str('+CMS ERROR').as(:cmd) >> str(': ') >> message }
+    rule(:merror) { (str('+CME ERROR') | str('+CMS ERROR')).as(:cmd) >> str(': ') >> int.as(:result) }
     rule(:mgl) do
       (str('+CMGL').as(:cmd) >> str(': ') >> infos >> crlf >> message >> crlf).repeat.as(:sms) >>
       crlf >> status