diff --git a/README.md b/README.md
index 1cb93ef..6ddacfa 100644
--- a/README.md
+++ b/README.md
@@ -11,10 +11,8 @@ It needs a few environment variables defined to work:
 
     PAGERDUTY_SCHEDULE_ID
     PAGERDUTY_API_TOKEN
-    PAGERDUTY_DOMAIN
 
-Those names should be fairly self-explanatory. The domain is the piece of your PagerDuty URL that is specific to you 
-i.e.  https://[PAGERDUTY_DOMAIN].pagerduty.com/
+Those names should be fairly self-explanatory.
 
 You can also optionally set PHONEDUTY_ANNOUNCE_TIME, which if set to a TRUEish value will include the current
 time of the engineer being called as part of the answering message. This may help raise awareness that you are potentially getting
diff --git a/app.json b/app.json
index 42b6d0c..8ef71b1 100644
--- a/app.json
+++ b/app.json
@@ -14,9 +14,6 @@
     },
     "PAGERDUTY_API_TOKEN": {
       "description": "PagerDuty API token"
-    },
-    "PAGERDUTY_DOMAIN": {
-      "description": "The name of your PagerDuty a/c, as it appears in the URL"
     }
   }
 }
diff --git a/composer.json b/composer.json
index e7e75cc..2563252 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
     "require": {
         "php": ">=5.3.8",
         "twilio/sdk": "dev-master",
-        "guzzlehttp/guzzle": "~4.0"
+        "guzzlehttp/guzzle": "~6.0"
     },
 
     "config": {
diff --git a/composer.lock b/composer.lock
index 70020a7..33112ee 100644
--- a/composer.lock
+++ b/composer.lock
@@ -1,51 +1,51 @@
 {
     "_readme": [
         "This file locks the dependencies of your project to a known state",
-        "Read more about it at http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "hash": "ec9a1474cc6bc44287f209ae972a9715",
+    "content-hash": "b91dd007773f546c262b1b91a29f2729",
     "packages": [
         {
             "name": "guzzlehttp/guzzle",
-            "version": "4.1.7",
+            "version": "6.3.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/guzzle/guzzle.git",
-                "reference": "448f2c2076cf0fb756230611491c4f7ecb735a29"
+                "reference": "407b0cb880ace85c9b63c5f9551db498cb2d50ba"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/448f2c2076cf0fb756230611491c4f7ecb735a29",
-                "reference": "448f2c2076cf0fb756230611491c4f7ecb735a29",
+                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/407b0cb880ace85c9b63c5f9551db498cb2d50ba",
+                "reference": "407b0cb880ace85c9b63c5f9551db498cb2d50ba",
                 "shasum": ""
             },
             "require": {
-                "ext-json": "*",
-                "guzzlehttp/streams": "~1.4",
-                "php": ">=5.4.0"
+                "guzzlehttp/promises": "^1.0",
+                "guzzlehttp/psr7": "^1.4",
+                "php": ">=5.5"
             },
             "require-dev": {
                 "ext-curl": "*",
-                "phpunit/phpunit": "~4.0",
-                "psr/log": "~1.0"
+                "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.4 || ^7.0",
+                "psr/log": "^1.0"
             },
             "suggest": {
-                "ext-curl": "Guzzle will use specific adapters if cURL is present"
+                "psr/log": "Required for using the Log middleware"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "4.1-dev"
+                    "dev-master": "6.3-dev"
                 }
             },
             "autoload": {
+                "files": [
+                    "src/functions_include.php"
+                ],
                 "psr-4": {
                     "GuzzleHttp\\": "src/"
-                },
-                "files": [
-                    "src/functions.php"
-                ]
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -58,7 +58,7 @@
                     "homepage": "https://github.com/mtdowling"
                 }
             ],
-            "description": "Guzzle is a PHP HTTP client library and framework for building RESTful web service clients",
+            "description": "Guzzle is a PHP HTTP client library",
             "homepage": "http://guzzlephp.org/",
             "keywords": [
                 "client",
@@ -69,27 +69,83 @@
                 "rest",
                 "web service"
             ],
-            "time": "2014-08-08 01:30:43"
+            "time": "2018-04-22T15:46:56+00:00"
+        },
+        {
+            "name": "guzzlehttp/promises",
+            "version": "v1.3.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/guzzle/promises.git",
+                "reference": "a59da6cf61d80060647ff4d3eb2c03a2bc694646"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/guzzle/promises/zipball/a59da6cf61d80060647ff4d3eb2c03a2bc694646",
+                "reference": "a59da6cf61d80060647ff4d3eb2c03a2bc694646",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.4-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "GuzzleHttp\\Promise\\": "src/"
+                },
+                "files": [
+                    "src/functions_include.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Michael Dowling",
+                    "email": "mtdowling@gmail.com",
+                    "homepage": "https://github.com/mtdowling"
+                }
+            ],
+            "description": "Guzzle promises library",
+            "keywords": [
+                "promise"
+            ],
+            "time": "2016-12-20T10:07:11+00:00"
         },
         {
-            "name": "guzzlehttp/streams",
-            "version": "1.5.1",
+            "name": "guzzlehttp/psr7",
+            "version": "1.5.2",
             "source": {
                 "type": "git",
-                "url": "https://github.com/guzzle/streams.git",
-                "reference": "fb0d1ee29987c2bdc59867bffaade6fc88c2675f"
+                "url": "https://github.com/guzzle/psr7.git",
+                "reference": "9f83dded91781a01c63574e387eaa769be769115"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/guzzle/streams/zipball/fb0d1ee29987c2bdc59867bffaade6fc88c2675f",
-                "reference": "fb0d1ee29987c2bdc59867bffaade6fc88c2675f",
+                "url": "https://api.github.com/repos/guzzle/psr7/zipball/9f83dded91781a01c63574e387eaa769be769115",
+                "reference": "9f83dded91781a01c63574e387eaa769be769115",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.4.0"
+                "php": ">=5.4.0",
+                "psr/http-message": "~1.0",
+                "ralouphie/getallheaders": "^2.0.5"
+            },
+            "provide": {
+                "psr/http-message-implementation": "1.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "~4.0"
+                "phpunit/phpunit": "~4.8.36 || ^5.7.27 || ^6.5.8"
             },
             "type": "library",
             "extra": {
@@ -99,10 +155,10 @@
             },
             "autoload": {
                 "psr-4": {
-                    "GuzzleHttp\\Stream\\": "src/"
+                    "GuzzleHttp\\Psr7\\": "src/"
                 },
                 "files": [
-                    "src/functions.php"
+                    "src/functions_include.php"
                 ]
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -114,15 +170,114 @@
                     "name": "Michael Dowling",
                     "email": "mtdowling@gmail.com",
                     "homepage": "https://github.com/mtdowling"
+                },
+                {
+                    "name": "Tobias Schultze",
+                    "homepage": "https://github.com/Tobion"
                 }
             ],
-            "description": "Provides a simple abstraction over streams of data (Guzzle 4+)",
-            "homepage": "http://guzzlephp.org/",
+            "description": "PSR-7 message implementation that also provides common utility methods",
+            "keywords": [
+                "http",
+                "message",
+                "psr-7",
+                "request",
+                "response",
+                "stream",
+                "uri",
+                "url"
+            ],
+            "time": "2018-12-04T20:46:45+00:00"
+        },
+        {
+            "name": "psr/http-message",
+            "version": "1.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/http-message.git",
+                "reference": "f6561bf28d520154e4b0ec72be95418abe6d9363"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/http-message/zipball/f6561bf28d520154e4b0ec72be95418abe6d9363",
+                "reference": "f6561bf28d520154e4b0ec72be95418abe6d9363",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Http\\Message\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
+            "description": "Common interface for HTTP messages",
+            "homepage": "https://github.com/php-fig/http-message",
             "keywords": [
-                "Guzzle",
-                "stream"
+                "http",
+                "http-message",
+                "psr",
+                "psr-7",
+                "request",
+                "response"
+            ],
+            "time": "2016-08-06T14:39:51+00:00"
+        },
+        {
+            "name": "ralouphie/getallheaders",
+            "version": "2.0.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/ralouphie/getallheaders.git",
+                "reference": "5601c8a83fbba7ef674a7369456d12f1e0d0eafa"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/ralouphie/getallheaders/zipball/5601c8a83fbba7ef674a7369456d12f1e0d0eafa",
+                "reference": "5601c8a83fbba7ef674a7369456d12f1e0d0eafa",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "~3.7.0",
+                "satooshi/php-coveralls": ">=1.0"
+            },
+            "type": "library",
+            "autoload": {
+                "files": [
+                    "src/getallheaders.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
             ],
-            "time": "2014-08-10 23:57:01"
+            "authors": [
+                {
+                    "name": "Ralph Khattar",
+                    "email": "ralph.khattar@gmail.com"
+                }
+            ],
+            "description": "A polyfill for getallheaders.",
+            "time": "2016-02-11T07:05:27+00:00"
         },
         {
             "name": "twilio/sdk",
@@ -130,25 +285,25 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/twilio/twilio-php.git",
-                "reference": "a876df2cd5bc873beb450a56e6e410680a5b4e4c"
+                "reference": "e54f54597849344edd40f86e12b17c1ac815e65b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/twilio/twilio-php/zipball/a876df2cd5bc873beb450a56e6e410680a5b4e4c",
-                "reference": "a876df2cd5bc873beb450a56e6e410680a5b4e4c",
+                "url": "https://api.github.com/repos/twilio/twilio-php/zipball/e54f54597849344edd40f86e12b17c1ac815e65b",
+                "reference": "e54f54597849344edd40f86e12b17c1ac815e65b",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.2.1"
+                "php": ">=5.5.0"
             },
             "require-dev": {
-                "mockery/mockery": ">=0.7.2",
-                "phpunit/phpunit": "3.7.*"
+                "apigen/apigen": "^4.1",
+                "phpunit/phpunit": "4.5.*"
             },
             "type": "library",
             "autoload": {
-                "psr-0": {
-                    "Services_Twilio": ""
+                "psr-4": {
+                    "Twilio\\": "Twilio/"
                 }
             },
             "license": [
@@ -156,12 +311,8 @@
             ],
             "authors": [
                 {
-                    "name": "Kevin Burke",
-                    "email": "kevin@twilio.com"
-                },
-                {
-                    "name": "Kyle Conroy",
-                    "email": "kyle+pear@twilio.com"
+                    "name": "Twilio API Team",
+                    "email": "api@twilio.com"
                 }
             ],
             "description": "A PHP wrapper for Twilio's API",
@@ -172,25 +323,25 @@
                 "twilio"
             ],
             "support": {
-                "source": "https://github.com/twilio/twilio-php/tree/master",
+                "source": "https://github.com/twilio/twilio-php/tree/5.30.2",
                 "issues": "https://github.com/twilio/twilio-php/issues"
             },
-            "time": "2014-07-15 17:50:20"
+            "time": "2019-03-15T20:38:12+00:00"
         }
     ],
     "packages-dev": [
         {
             "name": "heroku/heroku-buildpack-php",
-            "version": "v33",
+            "version": "v153",
             "source": {
                 "type": "git",
                 "url": "https://github.com/heroku/heroku-buildpack-php.git",
-                "reference": "5b715c36a6e0d3d1c9803e6409256633cdadf05b"
+                "reference": "59b9c4daeebd70eadc4ae3d394429e3f357c56e8"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/5b715c36a6e0d3d1c9803e6409256633cdadf05b",
-                "reference": "5b715c36a6e0d3d1c9803e6409256633cdadf05b",
+                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/59b9c4daeebd70eadc4ae3d394429e3f357c56e8",
+                "reference": "59b9c4daeebd70eadc4ae3d394429e3f357c56e8",
                 "shasum": ""
             },
             "bin": [
@@ -211,7 +362,7 @@
                 }
             ],
             "description": "Toolkit for starting a PHP application locally, with or without foreman, using the same config for PHP/HHVM and Apache2/Nginx as on Heroku",
-            "homepage": "http://github.com/heroku/heroku-buildpack-php",
+            "homepage": "https://github.com/heroku/heroku-buildpack-php",
             "keywords": [
                 "apache",
                 "apache2",
@@ -221,21 +372,18 @@
                 "nginx",
                 "php"
             ],
-            "time": "2014-08-07 21:25:54"
+            "time": "2019-03-19T00:24:16+00:00"
         }
     ],
-    "aliases": [
-
-    ],
+    "aliases": [],
     "minimum-stability": "stable",
     "stability-flags": {
         "twilio/sdk": 20
     },
     "prefer-stable": false,
+    "prefer-lowest": false,
     "platform": {
         "php": ">=5.3.8"
     },
-    "platform-dev": [
-
-    ]
+    "platform-dev": []
 }
diff --git a/src/Pagerduty.php b/src/Pagerduty.php
index ddc2c3f..b69c2d8 100644
--- a/src/Pagerduty.php
+++ b/src/Pagerduty.php
@@ -14,32 +14,28 @@
 
 class Pagerduty {
 
-    const DEFAULT_TIMEZONE = 'Pacific/Auckland';
+    const DEFAULT_TIMEZONE = 'Europe/Paris';
 
     protected $APItoken;
     protected $URL;
     protected $httpClient;
 
     /**
-     * Constructor. Expects an API token and PagerDuty domain.
+     * Constructor. Expects a PagerDuty API token.
      *
      * @param string $APItoken
-     * @param string $domain
      *
      */
-    public function __construct($APItoken, $domain) {
+    public function __construct($APItoken) {
         $this->APItoken = $APItoken;
-        $this->URL = "https://{$domain}.pagerduty.com/api/v1";
+        $this->URL = "https://api.pagerduty.com";
 
         $this->httpClient = new \GuzzleHttp\Client(
-            array('defaults' =>
-                array('headers' =>
-                    array(
-                        'Content-Type' => 'application/json',
-                        'Authorization' => "Token token={$APItoken}"
-                    )
-                )
-            )
+            ['headers' =>
+                [ 'Accept' => 'application/vnd.pagerduty+json;version=2',
+                  'Authorization' => "Token token=$APItoken"
+                ]
+            ]
         );
     }
 
@@ -62,7 +58,7 @@ public function getOncallUserForSchedule($scheduleID)
         $datetime->add(new DateInterval('PT1S'));
         $oneSecondLater = urlencode($datetime->format(DateTime::ISO8601));
 
-        $pagerDutyScheduleURL = "{$this->URL}/schedules/{$scheduleID}?since={$now}&until={$oneSecondLater}";
+        $pagerDutyScheduleURL = "{$this->URL}/schedules/{$scheduleID}?time_zone=UTC&since={$now}&until={$oneSecondLater}";
 
         $userID = null;
 
@@ -92,7 +88,11 @@ public function getUserDetails($userID)
     {
         // See http://developer.pagerduty.com/documentation/rest/users/show
         $pagerDutyUserURL = "{$this->URL}/users/{$userID}";
-        $queryString = array('query' => array('include[]' => 'contact_methods'));
+        $queryString = [
+            'query' => [
+                'include[]' => 'contact_methods'
+            ]
+        ];
 
         $response = $this->httpClient->get($pagerDutyUserURL, $queryString);
 
@@ -102,14 +102,14 @@ public function getUserDetails($userID)
             $json = json_decode($response->getBody(), true);
 
             foreach($json['user']['contact_methods'] as $method) {
-                if($method['type'] == 'phone') {
-                    $user = array(
+                if($method['type'] == 'phone_contact_method') {
+                    $user = [
                         'full_name'   => $json['user']['name'],
                         'first_name'  => $this->extractFirstName($json['user']['name']),
                         'local_time'    => $this->getCurrentTimeForTimezone(
                             $this->convertFriendlyTimezoneToFull($json['user']['time_zone'])),
-                        'phone_number' => "+{$method['country_code']}{$method['phone_number']}",
-                    );
+                        'phone_number' => "+{$method['country_code']}{$method['address']}",
+                    ];
                     break;
                 }
             }
@@ -331,3 +331,4 @@ protected function convertFriendlyTimezoneToFull($tz)
         return (array_key_exists($tz, $timezones) ? $timezones[$tz] : null);
     }
 }
+?>
diff --git a/web/index.php b/web/index.php
index 9b3d877..ff6fd27 100644
--- a/web/index.php
+++ b/web/index.php
@@ -16,31 +16,30 @@
 // Set these Heroku config variables
 $scheduleID = getenv('PAGERDUTY_SCHEDULE_ID');
 $APItoken   = getenv('PAGERDUTY_API_TOKEN');
-$domain     = getenv('PAGERDUTY_DOMAIN');
 
 // Should we announce the local time of the on-call person?
 // (helps raise awareness you might be getting somebody out of bed)
 $announceTime = getenv('PHONEDUTY_ANNOUNCE_TIME');
 
 
-$pagerduty = new \Vend\Phoneduty\Pagerduty($APItoken, $domain);
+$pagerduty = new \Vend\Phoneduty\Pagerduty($APItoken);
 
 $userID = $pagerduty->getOncallUserForSchedule($scheduleID);
 
 if (null !== $userID) {
     $user = $pagerduty->getUserDetails($userID);
 
-    $attributes = array(
-        'voice' => 'alice',
-        'language' => 'en-GB'
-    );
+    $attributes = [
+        'voice' => 'man',
+        'language' => 'en'
+    ];
 
     $time = "";
     if ($announceTime && $user['local_time']) {
         $time = sprintf("The current time in their timezone is %s.", $user['local_time']->format('g:ia'));
     }
 
-    $twilioResponse = new Services_Twilio_Twiml();
+    $twilioResponse = new \Twilio\TwiML\VoiceResponse();
     $response = sprintf("The current on-call engineer is %s. %s "
         . "Please hold while we connect you.",
         $user['first_name'],
@@ -48,7 +47,7 @@
         );
 
     $twilioResponse->say($response, $attributes);
-    $twilioResponse->dial( $user['phone_number']);
+    $twilioResponse->dial($user['phone_number']);
 
     // send response
     if (!headers_sent()) {
@@ -57,3 +56,4 @@
 
     echo $twilioResponse;
 }
+?>