To use Zoiper with X-Telecom telephony on smartphones (in this example, iPhone), follow these steps in order:

Instructions:

1. Get your SIP credentials after registration — they will be sent to your email and are also available in your control panel:  
   https://my.x-telecom.org/billing/devices/user_devices  
   You will see:
   • Login (numbers)
   • Password
   • Host — sip.x-telecom.org or IP 178.162.235.72  
      
2. In Zoiper, do not choose the suggested providers. Select Manual Configuration:
   • Settings → Accounts → + (Add Account)
   • First question: "Do you have a login and password?" — click YES

• Two options will appear: Choose provider or Manual Configuration. Select Manual Configuration
• Then choose SIP account  
   

1. Fill in the account details:
   • Account name: any name for your convenience
   • Domain/Host: sip.x-telecom.org or 178.162.235.72
   • Username: your SIP login
   • Password: your SIP password
   • Caller ID: leave empty (softphones often transmit it incorrectly)  
      
2. Advanced settings:

• In Auth Username, also enter your SIP login
• Tap Register (top button in Zoiper)  
   

1. Check registration result:
   • If successful, you will see OK
   • If not, a red error code will appear  
      
2. Making calls:
   • If you have sufficient funds in your account, you can start making calls

If you encounter any difficulties, you can always contact technical support: https://t.me/x-telecom_sup