What is a DID phone number?
A DID (Direct Inward Dial) is a phone number that the carrier delivers to your phone system. In modern terms it is just "a phone number you can receive calls on". The acronym is a holdover from the PBX era, when one trunk fed many extensions and the DID told the PBX which extension to ring.
Definition
Every phone call needs two numbers: a calling number (the customer's phone) and a called number (yours). The called number is the DID. Your carrier owns ranges of DIDs from the North American Numbering Plan (or international equivalents), assigns them to customers, and routes inbound calls to those DIDs through a SIP trunk.
How DIDs are provisioned
DIDs are provisioned in three steps:
- Search. Pick an area code or rate center. Carriers return available numbers.
- Claim. Buy the DID. The carrier marks it as belonging to you in their inventory.
- Route. Tell the carrier where to deliver calls: which SIP trunk, which fallback, what to do when ringing fails.
In message.com all three steps happen through the Phone numbers API. POST /phone-numbers/available searches. POST /phone-numbers claims and configures routing.
Routing strategies
A DID in message.com can route to:
all_agents. Any available agent in the workspace.department. Any available agent in a specific department.specific_agent. One named agent. Falls through to a fallback when offline.
The routing decision happens server-side when the carrier's webhook fires on ringing. If no agent is eligible, the call goes to voicemail.
Number types
| Type | Example | Notes |
|---|---|---|
| Local | +14155550100 | Standard area-code number. Cheapest. |
| Toll-free | +18005550100 | 800 / 833 / 844 / 855 / 866 / 877 / 888. Caller pays nothing. Sender pays per-minute. |
| Vanity | +18005551234 | Mnemonic letters that spell a brand. Same plumbing as toll-free. |
Porting an existing number
If you already have a DID at another carrier, you can port it into message.com. Porting requires a Letter of Authorization (LOA) and copies of the current carrier's bill. The process takes 2 to 4 weeks for local numbers, 7 to 14 days for toll-free. Until the port completes, the number keeps ringing at the old carrier.
E.164 format
DIDs in message.com are always stored in E.164 format: +, country code, national number, no separators. +14155550100, not (415) 555-0100. See E.164 for the format rules.