VoIP and GSM in Onoff — what's the difference?

VoIP and GSM in Onoff — what's the difference?

Onoff combines VoIP and GSM to deliver flexible, cost-effective business telephony. Here is what that means in practice for your organisation.

VoIP

Calls and messages travel over your Wi-Fi or mobile data connection (4G/5G), directly through the Onoff app.

What this gives you:

• Use the same number on up to three devices simultaneously
• Call and send messages from anywhere with an internet connection
• No roaming charges when travelling abroad
• Local numbers in multiple countries (France, Belgium, United States…)

GSM 

When your internet connection is unavailable or unreliable, calls can be forwarded to your main GSM line through your mobile operator.

⚠️ Please note — In GSM mode, your operator's standard rates apply, including any roaming charges. These fees are charged by your operator, not by Onoff.

Quick comparison

Which mode for which situation?

What Onoff changes in practice

No SIM card to manage — Onoff works as a secondary line running over your internet connection. Numbers are assigned directly from the admin console, with no physical SIM distribution required.

Local presence internationally — Your teams can have a local number in each market, without swapping SIM cards or incurring roaming fees.

Predictable costs — Over VoIP, no billing surprises. Over GSM fallback, costs depend solely on your operator plan.

Security — All Onoff communications, whether VoIP or GSM, are encrypted and managed through the centralised admin console.

🔵 Need help choosing the right setup? Contact our sales team for recommendations tailored to your organisation.