First install Grandstream via Google Play: https://play.google.com/store/apps/details?id=com.grandstream.wave Then Start Grandstream, go to Settings at the bottom right: Account Settings ==> Click + (New Account) In VOIP Providers select Boxis.net Fill SIP User ID, as well as Password, the account name can be anything. Then confirm with the up arrow. Then return to the account, in the network settings tab select "DNS MODE" and set to : NAPTR/SRV (On Iphone, you must uncheck the wifi mode: Advanced settings tab - uncheck only use Wi-Fi to register the account). Translated with www.DeepL.com/Translator