Telecoms glossary • C
Call Forwarding
Four independent rules that most people configure as one, which is how calls end up in a voicemail box nobody checks.
What is call forwarding?in VoIP and business telephony
1. Call forwarding sends an incoming call to a different number or extension instead of ringing the one that was dialled. On a business phone system it is set as four independent conditions: forward always, forward when busy, forward when there is no answer, and forward when the device cannot be reached at all.
2. Those conditions are separate settings that fire on different triggers. A no-answer rule does nothing when the internet drops, because that is the unreachable condition, and confusing the two is the commonest reason a carefully built fallback never runs.
The four conditions, and what triggers each
Every platform words these differently. The triggers are the same everywhere, and knowing which one fires when is the whole skill.
- Always
- Every call redirects immediately and the original extension never rings. Used when someone is out for the day, or when a number is pointed at a switchboard, an answering service or a voice agent. It overrides the other three, which is why a forgotten always rule is the first thing to check when an extension has stopped ringing.
- Busy
- Fires when the extension is already on a call. Without it the second caller gets an engaged tone. With it they reach a colleague, a hunt group or voicemail.
- No answer
- Fires after a timer, usually 15 to 20 seconds or four to five rings. The most used rule and the easiest to set badly: too short and callers never reach the person they wanted, too long and they hang up before anything happens.
- Unreachable
- Fires when the device is not registered at all: no power, no internet, app closed, handset unplugged. This is the outage rule. It is also the one most often left blank, because in normal operation nothing ever triggers it.
Rules can be layered by time of day and by day of week, so an after-hours forward and a lunchtime cover are the same feature with a schedule attached. Changes apply from the portal in seconds and need no site visit.
Building a cascade that actually catches calls
A working setup chains the conditions so that each failure hands off to the next destination rather than to voicemail. The sequence below is the one most South African offices settle on.
A four-stage forwarding cascade
The third stage is the one that earns its place. The mobile app and the mobile number are different destinations: the app needs data and a registered session, the number only needs cellular coverage. Pointing the unreachable rule at the app is a common mistake, because if the device is unreachable the app is exactly what is not working.
Who pays, and what the caller sees
A forward creates a second call. The inbound leg terminates on your phone system, then the system originates a new leg out to the forwarding destination, and that second leg is billed to your account at your provider’s rate for that destination.
Forwarding to an internal extension costs nothing. Forwarding to a mobile is a fixed-to-mobile call your business pays for, every time, for the whole duration of the conversation. A team of ten with no-answer rules pointing at ten mobiles has quietly moved its inbound calls onto outbound billing. Check the rate before rolling it out across the company, and watch the effect in your call management reports.
Caller identity is the other thing to specify. Providers differ on whether the forwarded leg presents the original caller’s number or your own business number, and the answer changes whether the person answering knows who is calling and whether return calls work. Ask, then test it with a real call before you rely on it.
Forwarding is not failover
Forwarding rules live on an extension inside the phone system. They only run if the phone system itself is reachable. On a cloud platform that holds true through a site outage, because the platform is in a data centre and only your handsets are dark. On an on-premise PBX it does not: if the site drops, the PBX drops with it and no extension rule executes.
The protection that survives that is set one level up, at the carrier, on the number itself. That is failover routing, and it is a separate configuration to request. Ask your provider what happens to an inbound call when your site is unreachable, and get the answer before you need it.
About this entry
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