The "give them a burner" advice is everywhere. The "use a travel eSIM" advice is everywhere. The honest answer about which one to use when is harder to find, because there isn't a single answer — there's a framework.
This is the version we walk founders through.
The four categories of phone number
Every operator should think about phone numbers as belonging to one of four categories. Each has a different sensitivity profile and a different right answer.
1. The public number
- What it's for: business cards, your website footer, suppliers, vendors
- Right tool: VoIP number (Google Voice, OpenPhone, or your CRM's number)
- Cost: $0–$25/month
- Why VoIP: it can ring on multiple devices, it can be reassigned in seconds, and losing your physical phone doesn't lose it
2. The verification number
- What it's for: banking, government, two-factor codes for high-value accounts
- Right tool: a dedicated SIM/eSIM on your primary carrier, never given to anyone
- Cost: $10–$30/month
- Why a real SIM: most banks still reject VoIP for verification; you need a real carrier line
3. The travel number
- What it's for: international roaming, local data abroad, calling colleagues from a foreign jurisdiction
- Right tool: travel eSIM (Airalo, Holafly, GigSky, Saily, or your carrier's international add-on)
- Cost: $5–$40 per trip
- Why a separate eSIM: cheaper than roaming, gives you a local data SIM, and isolates travel activity from your main line
4. The burner
- What it's for: a one-off project, a sensitive negotiation, dating apps, contractors you haven't vetted
- Right tool: VoIP burner number (Burner, Hushed) or a prepaid SIM if real-SIM is required
- Cost: $5–$15 for a few weeks of use
- Why burner: you throw it away when the use case ends, no lingering exposure
The decision
When a founder asks "what number should I give them?" — the answer is in the column they fit in, not in the type of person they are. A new investor goes in public. A new banking app goes in verification. A driver in Lagos goes in travel. An unverified consultant goes in burner.
Confusing the columns is what causes problems.
The travel eSIM specifically
In 2026, the practical travel-eSIM stack:
- Airalo or Saily for most countries — cheap, reliable, easy to top up
- Holafly for unlimited-data trips — more expensive but predictable
- Your carrier's international add-on for short business trips where you need to keep your number active
Three rules:
- Install the eSIM before you travel. Activation on landing in a country with no network is a problem you don't want.
- Test it for 5 minutes before you leave home. Half the headaches come from a mis-pasted activation code.
- Keep your home line as a secondary eSIM, set to data-off. You receive verification codes; you don't pay roaming.
When you actually need a burner
The honest list is shorter than people think:
- Press cycle: a number journalists can reach you on that you can quietly drop after the story
- Acquisitions or partnerships under NDA: a number where calls are deliberately contained
- Fieldwork in a region where your main number would be inconvenient or unwise to give out
- Personal protection during a sensitive period (divorce, public conflict, stalking)
If your reason isn't in that list, you don't need a burner. You need to use the public number you already have.
