No, a 2ndLine number won't affect your primary phone number at all. 
They work independently:

• 2ndLine uses VoIP: It relies on your internet connection (Wi-Fi or data) to make calls and send texts, separate from your SIM card.
• Different functions: You can keep your primary number for personal calls and use 2ndLine for business, online services, or privacy.

Benefits of using 2ndLine along with your primary number:

• Save money: Make cheap or even free international calls with 2ndLine, potentially lowering your overall phone bill.
• Enhanced privacy: Keep your personal number private when needed.
• Organize communication: Maintain separate lines for work and personal life.

Remember: Using 2ndLine doesn't affect your primary number's functionality or data plan. They work side-by-side for flexible and convenient communication.