What happens to your phones if the internet goes down
Calls keep arriving at your provider. Set up in advance where they should go when your office cannot answer.
What actually happens to your calls?
Hosted phones run over your internet connection, so if the connection drops, the handsets on the desks stop working. Your numbers do not. Calls still reach your provider, and whether they ring a mobile or fall into voicemail depends entirely on how you configured the account.
What to set up before you need it
| Option | What it does | Cost |
|---|---|---|
| Failover to mobiles | Calls forward to staff mobile numbers when the office is unreachable. | Usually included, though it has to be turned on |
| Mobile app on the same system | Staff answer their extension over cellular data. Callers see no difference. | Included with most seats |
| A second internet connection | A cheaper line from a different network takes over automatically. | The cost of a small broadband or fixed wireless plan |
| Cellular backup at the router | A SIM in the router covers short outages. | A modest monthly data plan |
| Out-of-hours message | A recorded message and voicemail instead of ringing out. | Free, and the minimum everyone should have |
Test it properly
Pick a quiet hour
Tell the team it is a test so nobody reports a fault.
Unplug the internet, not the phones
You want the real failure, not a simulated one.
Call your main number from a mobile
Check where it lands and how long it takes to get there.
Check the fallback of the fallback
If the mobile does not answer, does it reach voicemail, and does that voicemail get to anyone?
Repeat once a year
Staff change, mobile numbers change, and failover lists go stale quietly.
How this compares to copper
Copper lines usually survive a power cut because the line itself carries power. That is a genuine advantage, and it is why lifts and fire panels still use them. But copper fails too, and when it does you have no way to redirect the calls at all. A hosted system with failover configured is more resilient in practice, because the call can always be sent somewhere else.
If calls matter more than anything
- Run two connections from genuinely different networks, not two plans from one provider
- Keep the router and switches on a battery so a brief power cut does not take the phones
- Keep at least one direct route to the business for emergencies — a published mobile is enough
- Make sure someone is named as responsible for checking failover is still correct
Last reviewed September 14, 2026
