Incase of a toll free number, will failover DID work automatically if the primary DID fails?

Incase of a toll free number, will failover DID work automatically if the primary DID fails?

Yes—if you enable failover routing on your toll-free line, calls divert instantly to the backup DID when the primary returns a busy tone, SIP error, or times out.

Table of contents

  1. Quick answer
  2. How automatic failover works
  3. Configuring failover in <Your Portal>
  4. Testing & monitoring
  5. Edge cases & limitations
  6. FAQ

1 · Quick answer

Scenario

What happens

Primary DID rings & answers

Call connects normally.

Primary DID busy / unreachable / SIP 5xx

Carrier reroutes to the failover DID within < 1 s.

No failover DID configured

Caller hears busy tone or fast-busy.

2 · How automatic failover works

  1. Inbound call hits your toll-free number.
  2. Carrier checks the health of the primary DID (SIP OPTIONS/PING or HTTP callback).
  3. If the probe fails (busy, timeout, error), the call is silently diverted to the failover DID.
  4. Your backup endpoint rings; the caller hears no interruption.

3 · Configuring failover in <Your Portal>

Prerequisites

  • Admin role in the portal
  • Toll-free number + at least one verified backup DID
  • Separate trunk or endpoint for the backup (recommended)

Steps

  1. Voice → Toll-Free → ✏️ Edit
  2. Go to Inbound Routing → Failover
  3. Toggle Enable Failover and pick your backup DID
  4. Set Trigger rules:
    • SIP error codes (486, 503, ≥ 500)
    • Ring-timeout (e.g., 3 rings / 15 s)
  5. Click Save → status shows Protected within ~30 s

4 · Testing & monitoring

Test

Method

Expected result

SIP 503 injection

Temporarily block primary PBX

Call diverts to failover DID

Ring-timeout

Don’t answer primary for 20 s

Failover DID rings

Portal alerts

Voice → Alerts panel

“Primary unreachable” logged; email/SMS sent

Enable email/SMS alerts so ops staff know whenever failover activates.

5 · Edge cases & limitations

  • Failover only applies to inbound toll-free calls; outbound calls still originate from the configured trunk.
  • Carriers may bill a failover surcharge after N triggers/month.
  • Emergency calls (911/112) bypass custom failover rules.
  • Mapping both primary and backup to the same PBX offers no resilience—use different data centers or carriers.

6 · FAQ

Q: Can I add more than one failover DID?
A: Yes—use cascading rules (primary → failover 1 → failover 2).

Q: Will callers notice longer ring times?
A: Diversion happens at the carrier layer in < 1 s—usually imperceptible.

7 · Related articles

  • Creating a failover DID for toll-free numbers
  • Load-balancing inbound calls
  • SIP trunk health monitoring