How many DIDs will be associated with a tollfree number?

How many DIDs will be associated with a tollfree number?

Most carriers let you map 2 – 10 Direct Inward Dialing (DID) numbers to one toll-free line. Two is the minimum we recommend for redundancy; more may be useful for regional load-balancing, capacity, or disaster recovery.

Table of contents

  1. Quick answer
  2. Why link multiple DIDs?
  3. Typical carrier limits
  4. How to add DIDs in <Your Portal>
  5. Best-practice mapping rules
  6. Edge cases & limitations
  7. FAQ

1 · Quick answer

Carrier tier

Allowed DIDs per toll-free

SMB plan

2 – 3

Enterprise standard

Up to 5

Enterprise premium

Up to 10 (request basis)

Numbers above are industry averages—check your specific plan for the exact cap.

2 · Why link multiple DIDs?

  • Redundancy – If DID A is unreachable, DID B answers instantly.
  • Regional presence – Route West-coast calls to a US-West PBX and EU calls to an EU trunk.
  • Load balancing – Split high-volume campaigns across two SIP endpoints to avoid overflow.
  • Maintenance windows – Take one trunk offline without impacting toll-free availability.

3 · Typical carrier limits

Factor

Impact on max DIDs

Plan tier

Higher tiers usually raise the cap.

Regulatory zone

Some countries restrict to 2 mapped DIDs.

Toll-free traffic class

High-volume or conversational voice may allow more; 2-way SMS rarely exceeds 3.

Concurrency SLA

>100 CPS (calls/sec) often requires a dedicated route instead of stacked DIDs.

4 · How to add DIDs in

Prerequisites

  • Admin role in the portal
  • One active toll-free number
  • The extra DID(s) you want to map (verified and routable)

Steps

  1. Voice → Toll-Free → ✏️ Edit
  2. Go to Inbound Routing → DID Mappings
  3. Click + Add DID → select your new DID from the list
  4. Set Priority (1 = primary, 2 = backup) or choose Round-Robin
  5. Click Save → status changes to Mapped within 30 s

Success check: Dial the toll-free line twice—call 1 should hit DID 1; simulate a failure (block SIP) and call 2 should failover to DID 2.

5 · Best-practice mapping rules

Goal

Recommended rule

High availability

Priority-based: primary → secondary → tertiary

Load sharing

Round-robin across DIDs with equal weight

Geographic routing

Geo-IP match → closest DID/PBX

Campaign tracking

One DID per marketing source; tag calls in analytics

6 · Edge cases & limitations

  • Two-way SMS uses the origination DID, not the toll-free mapping.
  • Carriers may charge a mapping fee after the third DID.
  • Emergency services (e.g., 911/112) ignore DID mappings and use the registered toll-free address.
  • Mapping multiple DIDs to the same physical PBX offers no resilience—place backups in a separate data center.

7 · FAQ

Q: Can I exceed 10 DIDs?
A: Rarely; you’ll need a custom contract or dedicated toll-free trunk.

Q: Does each DID need its own SIP trunk?
A: No, but separate trunks improve fault isolation.

Q: Will adding more DIDs slow call setup?
A: Negligibly—carrier lookup adds < 1 ms per extra DID.

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