Yes, you can make calls to most phone numbers using 2ndLine subsription, thanks to VoIP technology. 

However, there are some limitations to keep in mind:

• Not all numbers are supported: Short service numbers (e.g., 911) and specific numbers from some mobile operators might not work.
• No USSD: We don't currently support USSD services (e.g., checking account balances).
• Country restrictions: In a few countries with limitations on internet-based calls, our service may not be accessible.

Despite these limitations, you can use the app to call most regular phone numbers, just like traditional telephony services. We're constantly working to expand our capabilities!