diff --git a/flexiapi/app/Http/Controllers/Account/RegisterController.php b/flexiapi/app/Http/Controllers/Account/RegisterController.php
index 72b1cae..4e5244e 100644
--- a/flexiapi/app/Http/Controllers/Account/RegisterController.php
+++ b/flexiapi/app/Http/Controllers/Account/RegisterController.php
@@ -109,7 +109,13 @@ class RegisterController extends Controller
         $request->validate([
             'terms' =>'accepted',
             'privacy' => 'accepted',
-            'username' => 'unique:external.accounts,username|nullable|filled',
+            'username' => [
+                Rule::unique('external.accounts', 'username')->where(function ($query) use ($request) {
+                    $query->where('domain', config('app.sip_domain'));
+                }),
+                'nullable',
+                new WithoutSpaces
+            ],
             'phone' => [
                 'required', 'unique:external.aliases,alias',
                 'unique:external.accounts,username',
diff --git a/flexisip-account-manager.spec b/flexisip-account-manager.spec
index 0c8756a..d0195d3 100644
--- a/flexisip-account-manager.spec
+++ b/flexisip-account-manager.spec
@@ -8,7 +8,7 @@
 #%define _datadir           %{_datarootdir}
 #%define _docdir            %{_datadir}/doc
 
-%define build_number 47
+%define build_number 48
 %define var_dir /var/opt/belledonne-communications
 %define opt_dir /opt/belledonne-communications/share/flexisip-account-manager
 %define env_file "$RPM_BUILD_ROOT/etc/flexisip-account-manager/flexiapi.env"