sms default sender name

app/services/sendinblue/sms_service.rb

 module Sendinblue
   class SmsService
+    DEFAULT_SENDER_NAME = 'Osuny'.freeze
+
     def self.send_mfa_code(user, code)
       duration =  ActiveSupport::Duration.build(Rails.application.config.devise.direct_otp_valid_for).inspect
       message = "#{code} est votre code d'authentification sur #{user.university} (valide #{duration})"
@@ -9,9 +11,12 @@ module Sendinblue
     private
 
     def self.send_message(user, message)
+      sender_name = user.university.sms_sender_name
+      sender_name ||= DEFAULT_SENDER_NAME
+
       api_instance = SibApiV3Sdk::TransactionalSMSApi.new
       send_transac_sms = SibApiV3Sdk::SendTransacSms.new(
-        sender: user.university.sms_sender_name,
+        sender: sender_name,
         recipient: user.mobile_phone,
         content: message
       )