diff --git a/src/PhoneFactory.php b/src/PhoneFactory.php
index d53e1f6..1cf5a70 100644
--- a/src/PhoneFactory.php
+++ b/src/PhoneFactory.php
@@ -67,17 +67,13 @@ protected function resolve($name)
     {
         $config = $this->getConfig($name);
 
-        if (is_null($config)) {
-            throw new InvalidArgumentException("Phone driver [{$name}] is not defined.");
-        }
-
         $driverMethod = 'create'.ucfirst($name).'Driver';
 
         if (method_exists($this, $driverMethod)) {
             return $this->{$driverMethod}($config);
         }
 
-        throw new InvalidArgumentException("Driver [{$config['driver']}] is not defined.");
+        throw new InvalidArgumentException("Method [{$driverMethod}] does not exist.");
     }
 
     /**
@@ -101,6 +97,10 @@ protected function createTwilioDriver(array $config)
      */
     protected function getConfig($name)
     {
+        if (! isset($this->config['drivers'][$name])) {
+            throw new InvalidArgumentException("Config driver [{$name}] is not defined.");
+        }
+
         return $this->config['drivers'][$name];
     }
 
diff --git a/src/PhoneValidator.php b/src/PhoneValidator.php
index 4da02bb..57b5c15 100644
--- a/src/PhoneValidator.php
+++ b/src/PhoneValidator.php
@@ -42,8 +42,8 @@ public function validatePhone(string $attribute, string $value, array $params)
      */
     public function validatePhoneCountry(string $attribute, string $value, array $params)
     {
-        if (count($params) < 1) {
-            throw new InvalidArgumentException('Validation rule phone_country requires at least 1 parameters.');
+        if (empty($params)) {
+            throw new InvalidArgumentException('Validation rule phone_country requires at least 1 parameter.');
         }
 
         try {
diff --git a/tests/FactoryTest.php b/tests/FactoryTest.php
index b45a44c..9fbfa5a 100644
--- a/tests/FactoryTest.php
+++ b/tests/FactoryTest.php
@@ -2,6 +2,7 @@
 
 namespace EllisIO\Tests\Phone;
 
+use InvalidArgumentException;
 use EllisIO\Phone\PhoneFactory;
 use EllisIO\Phone\Contracts\Driver;
 
@@ -30,6 +31,38 @@ public function testSetDefaultDriver()
         $this->assertSame('test', $factory->getDefaultDriver());
     }
 
+    public function testUndefinedConfig()
+    {
+        try {
+            $factory = $this->getFactory();
+            $factory->driver('test');
+        } catch (InvalidArgumentException $e) {
+            $this->assertStringStartsWith('Config driver', $e->getMessage());
+        }
+    }
+
+    public function testUndefinedDriver()
+    {
+        try {
+            $config = $this->app->config->get('phone');
+            $config['drivers']['test'] = [];
+
+            $factory = new PhoneFactory($config);
+            $factory->driver('test');
+        } catch (InvalidArgumentException $e) {
+            $this->assertStringStartsWith('Method', $e->getMessage());
+        }
+    }
+
+    public function testMagicCall()
+    {
+        $factory = $this->getFactory();
+        $phone1 = $factory->formatNumber('+14153902337');
+        $phone2 = $factory->driver()->formatNumber('+14153902337');
+
+        $this->assertSame($phone1, $phone2);
+    }
+
     protected function getFactory()
     {
         return new PhoneFactory($this->app->config->get('phone'));
diff --git a/tests/PhoneTest.php b/tests/PhoneTest.php
index 54ee170..d7ee802 100644
--- a/tests/PhoneTest.php
+++ b/tests/PhoneTest.php
@@ -3,9 +3,22 @@
 namespace EllisIO\Tests\Phone;
 
 use EllisIO\Phone\Phone;
+use InvalidArgumentException;
 
 class PhoneTest extends AbstractTestCase
 {
+    public function testE164Compliancy()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        new Phone('test', 'test', 'test');
+    }
+
+    public function testISO3166Alpha2Compliancy()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        new Phone('+14153902337', '(415) 390-2337', 'test');
+    }
+
     public function testGetNumber()
     {
         $phone = $this->getPhone();
diff --git a/tests/ValidatorTest.php b/tests/ValidatorTest.php
index 3751cba..3693e59 100644
--- a/tests/ValidatorTest.php
+++ b/tests/ValidatorTest.php
@@ -2,6 +2,7 @@
 
 namespace EllisIO\Tests\Phone;
 
+use InvalidArgumentException;
 use Illuminate\Support\Facades\Validator;
 
 class ValidatorTest extends AbstractTestCase
@@ -76,6 +77,13 @@ public function testValidatePhoneCountryCanadaFails()
         );
     }
 
+    public function testValidatePhoneCountryParamsLessThanZero()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $validator = $this->getValidator('4153902337', 'phone_country');
+        $this->assertTrue($validator->passes());
+    }
+
     protected function getValidator($phone, $rules)
     {
         return Validator::make([