diff --git a/.github/workflows/code-checks.yml b/.github/workflows/code-checks.yml
new file mode 100644
index 0000000..c17e30b
--- /dev/null
+++ b/.github/workflows/code-checks.yml
@@ -0,0 +1,48 @@
+name: CodeChecks
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php:
+          - '7.3'
+          - '7.4'
+          - '8.0'
+
+    name: PHP ${{ matrix.php }} tests
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: xdebug
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v2
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php${{ matrix.php }}-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php${{ matrix.php }}-
+
+      - name: Composer
+        run: composer install --no-progress
+
+      - name: PHPUnit
+        run: vendor/bin/phpunit --coverage-clover=coverage.xml
+
+      - name: "Upload coverage to Codecov"
+        uses: "codecov/codecov-action@v2"
+        with:
+          fail_ci_if_error: true
diff --git a/composer.json b/composer.json
index 153c76c..c5f4020 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
     ],
     "require": {
         "php": "^7.0",
-        "beberlei/assert": "^2.7",
+        "beberlei/assert": "^2.9",
         "guzzlehttp/guzzle": "~6.2",
         "psr/http-message": "~1.0",
         "symfony/options-resolver": "^3.0|^4.0",
diff --git a/src/Client.php b/src/Client.php
index 4e2095b..502d73a 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -15,7 +15,10 @@
 
 namespace D3\LinkmobilityClient;
 
+use D3\LinkmobilityClient\Exceptions\ApiException;
 use D3\LinkmobilityClient\Request\RequestInterface;
+use GuzzleHttp\RequestOptions;
+use Psr\Http\Message\ResponseInterface;
 
 class Client
 {
@@ -34,10 +37,11 @@ class Client
         $this->requestClient = $client ?: new \GuzzleHttp\Client( [ 'base_uri' => $this->apiUrl->getBaseUri() ] );
     }
 
-    public function request(RequestInterface $request) : ResponseInterface
+    public function request(RequestInterface $request) : \D3\LinkmobilityClient\Response\ResponseInterface
     {
         $request->validate();
         $responseClass = $request->getResponseClass();
+
         return $request->getResponseInstance(
             $this->rawRequest($request->getUri(), $request->getMethod(), $request->getOptions())
         );
@@ -48,22 +52,14 @@ class Client
      * @param string $method
      * @param array  $postArgs
      *
-     * @return string
+     * @return ResponseInterface
      * @throws ApiException
      * @throws GuzzleException
      */
-    protected function rawRequest( $url, string $method = RequestInterface::METHOD_GET, array $options = []): string
+    protected function rawRequest( $url, string $method = RequestInterface::METHOD_GET, array $options = []): ResponseInterface
     {
-        $options['headers']['Authorization'] = 'access_token '.$this->accessToken;
-        
-        if (!empty($body)) {
-            $options['json'] = $body;
-        }
-        dumpvar(__METHOD__.__LINE__.PHP_EOL);
-dumpvar($options);
-dumpVar($method);
-dumpvar($url);
-die();
+        $options['headers']['Authorization'] = 'Bearer '.$this->accessToken;
+
         $response = $this->requestClient->request(
             $method,
             $url,
diff --git a/src/Exceptions/ApiException.php b/src/Exceptions/ApiException.php
new file mode 100644
index 0000000..e1e5d40
--- /dev/null
+++ b/src/Exceptions/ApiException.php
@@ -0,0 +1,21 @@
+<?php
+
+/**
+ * This Software is the property of Data Development and is protected
+ * by copyright law - it is NOT Freeware.
+ * Any unauthorized use of this software without a valid license
+ * is a violation of the license agreement and will be prosecuted by
+ * civil and criminal law.
+ * http://www.shopmodule.com
+ *
+ * @copyright (C) D3 Data Development (Inh. Thomas Dartsch)
+ * @author        D3 Data Development - Daniel Seifert <support@shopmodule.com>
+ * @link          http://www.oxidmodule.com
+ */
+
+namespace D3\LinkmobilityClient\Exceptions;
+
+class ApiException extends LinkmobilityException
+{
+
+}
\ No newline at end of file
diff --git a/src/Exceptions/LinkmobilityException.php b/src/Exceptions/LinkmobilityException.php
new file mode 100644
index 0000000..7b056da
--- /dev/null
+++ b/src/Exceptions/LinkmobilityException.php
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * This Software is the property of Data Development and is protected
+ * by copyright law - it is NOT Freeware.
+ * Any unauthorized use of this software without a valid license
+ * is a violation of the license agreement and will be prosecuted by
+ * civil and criminal law.
+ * http://www.shopmodule.com
+ *
+ * @copyright (C) D3 Data Development (Inh. Thomas Dartsch)
+ * @author        D3 Data Development - Daniel Seifert <support@shopmodule.com>
+ * @link          http://www.oxidmodule.com
+ */
+
+declare(strict_types=1);
+
+namespace D3\LinkmobilityClient\Exceptions;
+
+class LinkmobilityException extends \Exception
+{
+
+}
\ No newline at end of file
diff --git a/src/Exceptions/RecipientException.php b/src/Exceptions/RecipientException.php
new file mode 100644
index 0000000..9e82f70
--- /dev/null
+++ b/src/Exceptions/RecipientException.php
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * This Software is the property of Data Development and is protected
+ * by copyright law - it is NOT Freeware.
+ * Any unauthorized use of this software without a valid license
+ * is a violation of the license agreement and will be prosecuted by
+ * civil and criminal law.
+ * http://www.shopmodule.com
+ *
+ * @copyright (C) D3 Data Development (Inh. Thomas Dartsch)
+ * @author        D3 Data Development - Daniel Seifert <support@shopmodule.com>
+ * @link          http://www.oxidmodule.com
+ */
+
+declare(strict_types=1);
+
+namespace D3\LinkmobilityClient\Exceptions;
+
+class RecipientException extends LinkmobilityException
+{
+
+}
\ No newline at end of file
diff --git a/src/RecipientsList/RecipientsList.php b/src/RecipientsList/RecipientsList.php
index 87ef2be..89bf13e 100644
--- a/src/RecipientsList/RecipientsList.php
+++ b/src/RecipientsList/RecipientsList.php
@@ -18,6 +18,7 @@ declare(strict_types=1);
 namespace D3\LinkmobilityClient\RecipientsList;
 
 use D3\LinkmobilityClient\ValueObject\Recipient;
+use libphonenumber\PhoneNumberType;
 
 class RecipientsList implements RecipientsListInterface, \Iterator
 {
@@ -26,14 +27,33 @@ class RecipientsList implements RecipientsListInterface, \Iterator
      */
     private $recipients = [];
 
-    public function add(Recipient $recipient)
+    public function add(Recipient $recipient) : RecipientsListInterface
     {
-        $this->recipients[md5(serialize($recipient))] = $recipient;
+        $phoneUtil = \libphonenumber\PhoneNumberUtil::getInstance();
+        try {
+            $phoneNumber = $phoneUtil->parse($recipient->get(), $recipient->getCountryCode());
+
+            if (false === $phoneUtil->isValidNumber($phoneNumber)) {
+                throw new \D3\LinkmobilityClient\Exceptions\RecipientException('invalid recipient phone number');
+            } elseif (false === in_array($phoneUtil->getNumberType($phoneNumber), [PhoneNumberType::MOBILE, PhoneNumberType::FIXED_LINE_OR_MOBILE])) {
+                throw new \D3\LinkmobilityClient\Exceptions\RecipientException('not a mobile number');
+            }
+
+            $this->recipients[md5(serialize($recipient))] = $recipient;
+        } catch (\libphonenumber\NumberParseException $e) {
+//            var_dump($e);
+        } catch (\D3\LinkmobilityClient\Exceptions\RecipientException $e) {
+//            var_dump($e);
+        }
+        
+        return $this;
     }
 
-    public function clearRecipents()
+    public function clearRecipents() : RecipientsListInterface
     {
         $this->recipients = [];
+
+        return $this;
     }
 
     public function getRecipients() : array
diff --git a/src/RecipientsList/RecipientsListInterface.php b/src/RecipientsList/RecipientsListInterface.php
index 0303328..5e10673 100644
--- a/src/RecipientsList/RecipientsListInterface.php
+++ b/src/RecipientsList/RecipientsListInterface.php
@@ -21,9 +21,9 @@ use D3\LinkmobilityClient\ValueObject\Recipient;
 
 interface RecipientsListInterface
 {
-    public function add(Recipient $recipient);
+    public function add(Recipient $recipient) : RecipientsListInterface;
 
-    public function clearRecipents();
+    public function clearRecipents() : RecipientsListInterface;
 
     public function getRecipients() : array;
 }
\ No newline at end of file
diff --git a/src/Request/Request.php b/src/Request/Request.php
index 3dad0dc..9ad4f6a 100644
--- a/src/Request/Request.php
+++ b/src/Request/Request.php
@@ -25,6 +25,7 @@ use D3\LinkmobilityClient\ValueObject\Recipient;
 use D3\LinkmobilityClient\ValueObject\Sender;
 use D3\LinkmobilityClient\ValueObject\SmsMessage;
 use D3\LinkmobilityClient\ValueObject\StringValueObject;
+use GuzzleHttp\RequestOptions;
 use OxidEsales\Eshop\Core\Registry;
 
 abstract class Request implements RequestInterface
@@ -125,7 +126,8 @@ abstract class Request implements RequestInterface
         Assert::that($this->getOptions())->isArray();
 
         Assert::that( $this->getRecipientsList() )->isInstanceOf(RecipientsList::class)->notEmpty();
-        Assert::thatAll( $this->getRecipientsList() )->isInstanceOf( Recipient::class );
+        Assert::that( $this->getRecipientsList()->getRecipients())->notEmpty();
+        Assert::thatAll( $this->getRecipientsList() )->isInstanceOf( Recipient::class )->notEmpty();
 
         // optional properties
         Assert::thatNullOr( $this->getClientMessageId() )->string();
@@ -151,10 +153,10 @@ abstract class Request implements RequestInterface
             'priority'          => $this->getPriority(),
             'recipientAddressList'  => $this->getRecipientsList()->getRecipients(),
             'sendAsFlashSms'    => $this->getSendAsFlashSms(),
-            'senderAddress'     => $this->getSenderAddress()->get(),
+            'senderAddress'     => $this->getSenderAddress() ? $this->getSenderAddress()->get() : null,
             'senderAddressType' => $this->getSenderAddressType(),
             'test'              => $this->isTest(),
-            'validityPeriode'    => $this->getValidityPeriode()
+            'validityPeriode'   => $this->getValidityPeriode()
         ];
     }
 
@@ -166,7 +168,7 @@ abstract class Request implements RequestInterface
 
         switch ($this->getContentType()) {
             case RequestInterface::CONTENTTYPE_JSON:
-                return ['json'  => json_encode($body)];
+                return [RequestOptions::JSON  => $body];
             default:
                 return $body;
         }
@@ -180,7 +182,6 @@ abstract class Request implements RequestInterface
                     'Accept'            => $this->contentType,
                     'Content-Type'      => $this->contentType,
                 ]
-
             ],
             $this->getBody()
         );
@@ -382,9 +383,9 @@ abstract class Request implements RequestInterface
     }
 
     /**
-     * @return string|null
+     * @return Sender|null
      */
-    public function getSenderAddress() : Sender
+    public function getSenderAddress()
     {
         return $this->senderAddress;
     }
@@ -444,6 +445,7 @@ abstract class Request implements RequestInterface
      */
     public function getResponseInstance(\Psr\Http\Message\ResponseInterface $rawResponse): ResponseInterface
     {
-        return new $this->getResponseClass($rawResponse);
+        $FQClassName = $this->getResponseClass();
+        return new $FQClassName($rawResponse);
     }
 }
\ No newline at end of file
diff --git a/src/Response/Response.php b/src/Response/Response.php
index 1373620..fbff257 100644
--- a/src/Response/Response.php
+++ b/src/Response/Response.php
@@ -8,26 +8,78 @@ use Assert\Assert;
 
 abstract class Response implements ResponseInterface
 {
+    const STATUSCODE        = 'statusCode';
+    const STATUSMESSAGE     = 'statusMessage';
+    const CLIENTMESSAGEID   = 'clientMessageId';
+    const TRANSFERID        = 'transferId';
+    const SMSCOUNT          = 'smsCount';
+
     /**
-     * @var array
+     * @var \Psr\Http\Message\ResponseInterface
      */
-    protected $data;
+    protected $rawResponse;
+
+    protected $content;
 
     /**
      * @var int
      */
     protected $status;
 
-    public function __construct(array $data)
+    public function __construct(\Psr\Http\Message\ResponseInterface $rawResponse)
     {
-        Assert::that($data)->keyExists('status');
+        $this->rawResponse = $rawResponse;
+        $this->content = json_decode($this->rawResponse->getBody()->getContents(), true);
+    }
+    
+    public function getRawResponse() : \Psr\Http\Message\ResponseInterface
+    {
+        return $this->rawResponse;
+    }
 
-        $this->data = $data;
-        $this->status = (int)$this->data['status'];
+    public function getContent()
+    {
+        return $this->content;
+    }
 
-        if ($this->isSuccessful()) {
-            $this->init();
-        }
+    /**
+     * @return int
+     */
+    public function getInternalStatus() : int
+    {
+        return $this->getContent()[self::STATUSCODE];
+    }
+
+    /**
+     * @return string
+     */
+    public function getStatusMessage() : string
+    {
+        return $this->getContent()[self::STATUSMESSAGE];
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getClientMessageId()
+    {
+        return $this->getContent()[self::CLIENTMESSAGEID];
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getTransferId()
+    {
+        return $this->getContent()[self::TRANSFERID];
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getSmsCount() : int
+    {
+        return $this->getContent()[self::SMSCOUNT];
     }
 
     /**
@@ -35,11 +87,13 @@ abstract class Response implements ResponseInterface
      */
     public function isSuccessful(): bool
     {
-        return $this->status >= 200 && $this->status < 300;
+        $status = $this->getInternalStatus();
+
+        return $status >= 2000 && $status <= 2999;
     }
 
-    public function getError(): string
+    public function getErrorMessage(): string
     {
-        return $this->isSuccessful() ? '' : $this->data['message'];
+        return $this->isSuccessful() ? '' : $this->getStatusMessage();
     }
 }
diff --git a/src/Response/ResponseInterface.php b/src/Response/ResponseInterface.php
index 351d9fb..66cae6d 100644
--- a/src/Response/ResponseInterface.php
+++ b/src/Response/ResponseInterface.php
@@ -6,24 +6,21 @@ namespace D3\LinkmobilityClient\Response;
 
 interface ResponseInterface
 {
-    /**
-     * Should instantiate the object from the data given
-     */
-    public function init() : void;
+    public function __construct(\Psr\Http\Message\ResponseInterface $rawResponse);
 
-    public function __construct(array $data);
+    public function getRawResponse() : \Psr\Http\Message\ResponseInterface;
 
-    /**
-     * Must return true if the request was successful
-     *
-     * @return bool
-     */
-    public function isSuccessful() : bool;
+    public function getInternalStatus() : int;
 
-    /**
-     * This must return the error, if any occurred, else it must return ''
-     *
-     * @return string
-     */
-    public function getError() : string;
+    public function getStatusMessage() : string;
+
+    public function getClientMessageId();
+
+    public function getTransferId();
+
+    public function getSmsCount() : int;
+
+    public function isSuccessful(): bool;
+
+    public function getErrorMessage(): string;
 }
diff --git a/src/SMS/TextRequest.php b/src/SMS/TextRequest.php
index 0582b00..f595863 100644
--- a/src/SMS/TextRequest.php
+++ b/src/SMS/TextRequest.php
@@ -133,7 +133,7 @@ class TextRequest extends \D3\LinkmobilityClient\Request\Request
 
     public function getUri(): string
     {
-        return '/smsmessaging/text/';
+        return '/rest/smsmessaging/text';
     }
 
     public function validate(): void
diff --git a/src/ValueObject/Recipient.php b/src/ValueObject/Recipient.php
index 77e7b28..4960e00 100644
--- a/src/ValueObject/Recipient.php
+++ b/src/ValueObject/Recipient.php
@@ -5,21 +5,36 @@ declare(strict_types=1);
 namespace D3\LinkmobilityClient\ValueObject;
 
 use Assert\Assert;
+use libphonenumber\PhoneNumberType;
 
 class Recipient extends StringValueObject
 {
-    public function __construct(string $value)
+    /**
+     * @var string
+     */
+    private $countryCode;
+
+    public function __construct(string $number, string $iso2CountryCode)
     {
-        // ohne +, dafür mit Ländervorwahl
-        // eine führende 0 scheint lokale Version
-        // zwei führende Nullen einfach weggeschnitten
+        Assert::that($iso2CountryCode)->string()->length(2);
 
-        //https://github.com/matmar10/msisdn-format-bundle/blob/master/Matmar10/Bundle/MsisdnFormatBundle/Resources/config/msisdn-country-formats.xml
+        $phoneUtil = \libphonenumber\PhoneNumberUtil::getInstance();
+        try {
+            $phoneNumber = $phoneUtil->parse($number, strtoupper($iso2CountryCode));
+            $number = ltrim($phoneUtil->format($phoneNumber, \libphonenumber\PhoneNumberFormat::E164), '+');
+        } catch (\libphonenumber\NumberParseException $e) {
+            var_dump($e);
+        }
 
+        parent::__construct($number);
+        $this->countryCode = $iso2CountryCode;
+    }
 
-        // valid formats can be found here: https://linkmobility.atlassian.net/wiki/spaces/COOL/pages/26017807/08.+Messages#id-08.Messages-recipients
-        Assert::that($value)->regex('/^(\+|c)?[0-9]+$/i', 'Recipient does not match valid phone number.');
-
-        parent::__construct($value);
+    /**
+     * @return string
+     */
+    public function getCountryCode() :string
+    {
+        return $this->countryCode;
     }
 }
diff --git a/src/ValueObject/Sender.php b/src/ValueObject/Sender.php
index 7d3a3ac..e82de54 100644
--- a/src/ValueObject/Sender.php
+++ b/src/ValueObject/Sender.php
@@ -8,13 +8,22 @@ use Assert\Assert;
 
 class Sender extends StringValueObject
 {
-    public function __construct(string $value)
+    public function __construct(string $number, string $iso2CountryCode)
     {
-        // if the sender is alphanumeric, test the length
-        if (!preg_match('/^\+[0-9]+$/i', $value)) {
-            Assert::that($value)->maxLength(11);
+        Assert::that($iso2CountryCode)->string()->length(2);
+
+        $phoneUtil = \libphonenumber\PhoneNumberUtil::getInstance();
+        try {
+            $phoneNumber = $phoneUtil->parse( $number, strtoupper($iso2CountryCode) );
+            $number      = $phoneUtil->format( $phoneNumber, \libphonenumber\PhoneNumberFormat::E164 );
+
+            if (false === $phoneUtil->isValidNumber($phoneNumber)) {
+                throw new \D3\LinkmobilityClient\Exceptions\RecipientException( 'invalid sender phone number' );
+            }
+        } catch (\libphonenumber\NumberParseException $e) {
+            var_dump($e);
         }
 
-        parent::__construct($value);
+        parent::__construct( $number);
     }
 }
diff --git a/src/ValueObject/SmsMessage.php b/src/ValueObject/SmsMessage.php
index a8a9b2b..88ab561 100644
--- a/src/ValueObject/SmsMessage.php
+++ b/src/ValueObject/SmsMessage.php
@@ -12,9 +12,9 @@ class SmsMessage extends StringValueObject
     const GSM_7BIT = '7-bit';
     const GSM_UCS2 = 'ucs-2';
 
-    public function __construct(string $value)
+    public function __construct(string $number)
     {
-        parent::__construct($value);
+        parent::__construct( $number);
 
         $smsLength = new SmsLength($this->value);
         $smsLength->validate();
diff --git a/src/ValueObject/StringValueObject.php b/src/ValueObject/StringValueObject.php
index 0e90e3f..0dc9611 100644
--- a/src/ValueObject/StringValueObject.php
+++ b/src/ValueObject/StringValueObject.php
@@ -8,11 +8,11 @@ use Assert\Assert;
 
 abstract class StringValueObject extends ValueObject
 {
-    public function __construct(string $value)
+    public function __construct(string $number)
     {
-        Assert::that($value)->notEmpty();
+        Assert::that( $number)->notEmpty();
 
-        $this->value = $value;
+        $this->value = $number;
     }
 
     public function __toString()
diff --git a/todo.txt b/todo.txt
new file mode 100644
index 0000000..9914677
--- /dev/null
+++ b/todo.txt
@@ -0,0 +1,2 @@
+RecipientsList als eigene Klasse
+Debug mit none, error, all log