Direct Inward Dial (DID)
Direct Inward Dial (DID) is a telephony service from a carrier that assigns a block of phone numbers to a single inbound trunk, allowing each number to ring through to a specific destination without an operator.
Definition
Direct Inward Dial (DID) is a telephony service from a carrier that assigns a block of phone numbers to a single inbound trunk, allowing each number to ring through to a specific destination without an operator. In Salesforce contact centers, DID is the underlying service that makes routed inbound numbers possible: your sales line, support line, and warranty line might all share one trunk, but DID assigns separate numbers that DNIS-based routing in Service Cloud Voice or another CTI system uses to route each call to the right queue.
DID has nothing specific to Salesforce; it is a generic telephony concept. What matters in the Salesforce context is that DID is the layer that provides numbers, while DNIS is the layer that identifies which DID number was dialed, and Service Cloud Voice or another CTI integration is the layer that turns DNIS into a routing decision. Buying DID service from your carrier is the prerequisite for everything downstream.
How DID fits Salesforce contact-center telephony
What DID provides at the telephony layer
A DID service from a carrier gives you a block of telephone numbers (often 10, 100, or 1000 at a time) and routes them all to the same physical inbound trunk. Without DID, your trunk would have one number and every inbound call would land there. With DID, the trunk receives the number that was dialed as part of the call setup (the DNIS signal), and your PBX or contact center routes from there.
DID number-block economics
Carriers price DID by block size: a block of 100 numbers is roughly 10x the cost of 10 numbers, with bulk discounts for larger blocks. Toll-free numbers (1-800, 1-888, 1-877) are separate from local DID blocks and priced differently. Per-call minutes are billed on top of the block, with toll-free typically paid by the receiving party and local DID by the calling party (the customer).
DID and Service Cloud Voice
Service Cloud Voice is hosted on Amazon Connect. To make Service Cloud Voice work with inbound numbers, you either claim numbers directly from Amazon Connect''s DID pool (US, EU, several other regions) or port your existing numbers from another carrier into Amazon Connect. Either path gives you DID-backed numbers that Service Cloud Voice surfaces as DNIS in Contact Flows.
Number porting and the cutover
Moving existing numbers into Service Cloud Voice means porting them from your current carrier. Porting is paperwork-heavy (Letters of Authorization, FOC dates, regulatory filings) and takes weeks. Salesforce supports the process through Amazon Connect''s number-porting wizard, but timelines are often outside your control because the losing carrier and the gaining carrier coordinate the actual cutover.
DID and SIP trunk architecture
Under the hood, DID is delivered over SIP (Session Initiation Protocol) trunks for modern carriers. The trunk carries multiple simultaneous calls, each tagged with the DID number that was dialed (DNIS). Service Cloud Voice and other modern CTI platforms expect SIP-delivered DID; older T1/PRI trunk technology still works but is increasingly legacy.
DID number management at scale
Large contact centers manage hundreds or thousands of DID numbers across campaigns, regions, and product lines. Salesforce Service Cloud Voice surfaces these as Phone Numbers in Setup with metadata: which queue routes the call, which IVR is the entry point, which campaign the number belongs to. Audit DID inventory quarterly: stale numbers from old campaigns accumulate fast.
DID and call analytics
Each DID number''s call volume and patterns flow into Service Cloud Voice analytics. Useful per-DID metrics: total call volume, abandonment rate, average handle time, post-call CSAT. Campaign attribution often hinges on unique DID numbers per channel; analytics tie marketing spend to actual call outcomes through DID-level reporting.
How to add inbound DID numbers to Service Cloud Voice
Adding DID numbers means either claiming new ones from Amazon Connect''s pool or porting existing ones from a carrier. Both flows happen in the Amazon Connect console accessible from Service Cloud Voice.
- Open the Amazon Connect Phone Numbers page
In Service Cloud Voice, open the Amazon Connect console. Navigate to Routing, then Phone Numbers.
- Claim a new number
Click Claim a number. Select the country, the type (DID local, DID toll-free, UIFN), and pick from the available numbers. Confirm the claim; the number is yours within minutes.
- Port an existing number (alternative)
Click Port a number to bring in an existing DID. Complete the porting form: current carrier, account number, billing address, Letter of Authorization. Amazon Connect coordinates with your current carrier; expect 2 to 4 weeks for the port to complete.
- Assign the number to a Contact Flow
Once claimed or ported, edit the number and pick a Contact Flow. Incoming calls to this number will enter that flow, which can read the DNIS (the number itself) and branch routing accordingly.
- Test the inbound flow
Call the number from a personal phone. Confirm the call hits the right Contact Flow and routes to the expected queue. Watch the Salesforce screen pop for any agent that picks up.
- Track the number in Salesforce analytics
Build a Salesforce report on the VoiceCall object filtered by DialedNumber. Per-DID call volume and outcomes appear here; use them for campaign attribution and capacity planning.
Local phone numbers from a specific country and area. Per-call minutes billed to the calling party.
1-800, 1-888, 1-877 numbers. Per-call minutes billed to the receiving party (your org).
International toll-free numbers (00800 prefix). Cross-border free for the caller.
An existing DID brought into Amazon Connect from another carrier. Preserves your published number through the transition.
- DID porting takes weeks. Plan the cutover carefully; published numbers cannot ring through during the brief porting window.
- Toll-free numbers are billed per minute received. High-volume support lines can incur significant cost on toll-free that local DID would avoid.
- Number portability requirements vary by country. Porting numbers internationally has more constraints than within one country.
- Amazon Connect number pools are not unlimited. Specialty area codes or vanity numbers may not be available; check before promising a specific number.
Trust & references
Straight from the source - Salesforce's reference material on Direct Inward Dial (DID).
- Service Cloud Voice OverviewSalesforce Help
- Amazon Connect Phone NumbersAWS Documentation
Hands-on resources to go deeper on Direct Inward Dial (DID).
About the Author
Dipojjal Chakrabarti is a B2C Solution Architect with 29 Salesforce certifications and over 13 years in the Salesforce ecosystem. He runs salesforcedictionary.com to help admins, developers, architects, and cert/interview candidates sharpen their fundamentals. More about Dipojjal.
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