Three outages, three fallbacks
The first question to ask is not “do we have a backup?” but “what does a customer who calls us during the outage hear?”. The answer changes depending on where the outage occurs.
| Outage | What the company experiences | What the caller hears | Usual fallback |
|---|
| The building (power, disaster, access) | Office phones are off | With a hosted phone system, the phone system still answers; calls can follow the planned rules | Mobile and desktop apps, forwarding to mobiles |
| The site’s Internet link | The site’s phones can no longer reach the phone system | The hosted phone system answers; the site’s phones no longer ring | Second link, connection sharing, forwarding or switching to mobile apps |
| The phone system platform | No phone works anymore, whatever the site | Depending on the carrier: busy tone, message or planned forwarding | Restoration by the operator; number forwarding prepared with the carrier |
The table assumes a hosted phone system. With an IP PBX installed on the premises, the first two rows merge with the third: if the building or its link goes down, the phone system goes down with it, for all the sites that depend on it. The comparison of architectures is in VoIP, SIP, IP PBX and UCaaS: which architecture.
Prepare before the outage
Most fallbacks are decided in calm conditions. During the outage, it is too late to find the right contact at the carrier.
- Apps. An employee who has the phone app on their mobile or computer remains reachable on their business number from any connection. It is the simplest fallback against a building or link outage.
- Fallback forwarding. What should the phone system do when nobody answers at a site? Forward reception to an on-call mobile, another site, or an announcement. These rules are prepared with the operator.
- A second link. For a site where the phone is critical, a second Internet connection, from another carrier or over a mobile network, prevents a single outage from isolating the team.
- Number forwarding at the carrier. If the platform itself is unavailable, only the carrier holding your numbers can route them elsewhere. What is possible, and how quickly, is agreed with them in advance.
- The contact list. Whom to call at the operator and at the carrier, with which numbers, when your own phone system is no longer working.
What a backup restores
A telephony backup is used to return the phone system to the state it was in: configuration, accounts, greeting rules, call queues, voicemail and, where applicable, recordings. It does not restore a dropped call. Nor does it replace forwarding: during the restore, it is the prepared fallbacks that keep the company reachable.
Two indicators describe what you can expect.
RTO (recovery time objective): the target time to get the service running again. RPO (recovery point objective): the amount of data you accept to lose, expressed as time elapsed since the last backup.
For a phone system backed up once a day, the RPO is counted in hours, not minutes. A change made in the morning, for example a new extension or a changed announcement, may need to be redone after a restore from the previous day. That is acceptable for a configuration that changes little, as long as you know it.
Retention matters too. A backup kept for thirty days makes it possible to go back to before a configuration error discovered late, or before a compromise. Beyond that, the earlier state no longer exists.
Multiple sites: centralizing shifts the risk
A central phone system for all sites simplifies reception and administration. In return, if it goes down, it goes down for everyone. Separate phone systems limit an outage to one site, but multiply operations, updates and backups.
With a hosted central phone system, a link outage affects only the site concerned: the others carry on, and calls intended for the isolated site can be forwarded. A general outage can only come from the platform itself. That is what you then need to question: how it is monitored, backed up and brought back into service, and how quickly.
How to actually set up multiple sites on Klytic Tel is described in Connecting multiple sites to Klytic Tel. For email, the same logic is covered in Email backup and continuity.
Example: a branch without an Internet link
A hypothetical case. A network of three real estate agencies uses a hosted phone system. Roadworks cut the fiber to one of them for the day.
The other two agencies notice nothing. In the cut-off agency, the desk phones no longer work, but the agents have the app on their mobiles and keep receiving calls on their direct numbers. The agency’s reception line is forwarded to the manager’s mobile, as planned. No customer heard a busy tone.
That day, the backup was of no use: nothing was lost. It would have been needed if the phone system itself had been damaged.
Frequently asked questions
Is a backup enough to ensure continuity?
No. It allows the phone system to be restored. In the meantime, forwarding and apps keep the company reachable.
Are calls in progress saved?
No. A dropped call has to be placed again. Only the configuration and the service data are restored.
Is an on-premises IP PBX more resilient?
It does not depend on the Internet for internal calls, but it stops when the building does. See VoIP, SIP, IP PBX and UCaaS.
How do I request a restore?
At Klytic, through support, covering the last 30 days. It is included in the event of a service malfunction, a deliberate deletion by an employee or an account deleted too early when someone leaves (up to 3 requests per month), or an attack suffered despite properly protected workstations. After an accidental deletion, a handling error, or if workstations were insufficiently protected, it is handled through a paid support ticket. See Security & backup.
Where Klytic fits
With Klytic Tel, each organization has its own phone server, hosted by default in a European cloud, in Mauritius or in a geographic zone compliant with the applicable jurisdiction, at your request, or installed on your servers. In the cloud, Klytic Tel relies on a leading cloud hosting provider, with an enterprise-grade availability commitment of 99.99% (excluding planned maintenance announced in advance) and failover between several hosting sites in the event of an outage: resilience to outages is very high. Klytic can also deploy the solution with another cloud provider of your choice. The platforms are monitored continuously. For multiple sites, telephony can rely on a single server or on several servers associated with sites and connected to one another: an outage of one server then remains limited to the sites it serves, and internal calls between sites remain free and secure.
Telephony is backed up every day. Backups are encrypted, replicated across several sites, immutable and kept for 30 days; restores are tested every month. The published objectives are a return to service in under 4 hours (RTO) and a maximum data loss of 24 hours for Klytic Tel (RPO). For email, documents and CRM, which are backed up every hour, the target RPO is under 2 hours. A restore is requested through support. It is included in the event of a service malfunction, a deliberate deletion by an employee or an account deleted too early when someone leaves (up to 3 requests per month), or an attack suffered despite properly protected workstations. After an accidental deletion, a handling error, or if workstations were insufficiently protected, it is handled through a paid support ticket.
Apps for mobile, computer and browser make it possible to stay reachable outside the office. Fallback forwarding is configured with Klytic during setup. How your numbers can be routed elsewhere while the platform is unavailable depends on what has been prepared with the carrier that holds them, Klytic or your current carrier.
Klytic does not publish any automatic failover to a second platform: this guide does not assume one. If your business requires it, raise it before setup.
Sources
Consulted in October 2026.
- Klytic, frequently asked questions: daily backup of Klytic Tel, hourly for the other offerings, 30-day retention, RTO of under 4 hours, RPO of under 2 hours and of 24 hours for Klytic Tel; continuous monitoring. klytic.com
- Klytic, Security & backup: encrypted, multi-site, immutable backups, restores tested every month, restore via support. klytic.com
- Klytic, Klytic Tel page: dedicated server, mobile and desktop apps, forwarding, multi-site, keep your carrier or use Klytic plans. klytic.com
