Adding the issued at claims, and remove 5 seconds to the not before (in case we have a clock skew)

app/Main.php

@@ -70,7 +70,7 @@ class Main extends Controller {
         elseif ($f3->get('VERB') == 'POST'){
             // Create the call
             // Generate a jwt token
-            $token = JWT::encode(array('api' => JWT_TOKEN, 'nbf' => time(), 'exp' => time() + 10 * 60), JWT_KEY);
+            $token = JWT::encode(array('api' => JWT_TOKEN, 'nbf' => time() - 5 , 'exp' => time() + 10 * 60, 'iat' => time()), JWT_KEY);
             // To get the callee, we have the callee_id in the form. Using that
             // to load the callee and retrieve its number.
             $contact = Api::get_contact($args['id']);

app/SIP.php

@@ -25,7 +25,7 @@ class SIP extends Controller {
         );
         $client = new GuzzleHttp\Client(['base_uri' => SIP_API]);
         try {
-            $token = JWT::encode(array('api' => JWT_TOKEN), JWT_KEY);
+            $token = JWT::encode(array('api' => JWT_TOKEN, 'nbf' => time() - 5, 'exp' => time() + 10*60, 'iat' => time()), JWT_KEY);
             $res = $client->get("calls/$call_id", ['query' => $data]);
             $f3->set('response', (GuzzleHttp\Psr7\copy_to_string($res->getBody())));
         } catch (RequestException $e) {