# CNAM IN for SIP trunks Caller Name Delivery (CNAM) provides a name associated with a telephone number. CNAM IN is the inbound service. It looks up the name associated with the caller ID of an incoming call and delivers the result to the receiving SIP endpoint. This can help agents and applications identify callers before answering or processing a call. CNAM IN does not authenticate the caller ID or change the calling number. It is also separate from CNAM OUT, which provides a caller name for an outbound call. See [Caller ID and CNAM OUT](../../../outbound-trunks/caller-id-cnam-out.html) for outbound behavior. ## How CNAM IN works CNAM lookup is an optional inbound SIP trunk service. **Enable CNAM Lookup** is disabled by default and applies to calls with a United States caller ID. When the setting is enabled, DIDWW queries a remote CNAM database and handles the result as follows: ``` %%{init: { "theme": "base", "themeVariables": { "fontSize": "14px", "primaryColor": "#e0f2fe", "primaryBorderColor": "#38bdf8", "primaryTextColor": "#1f2d3d", "secondaryColor": "#ccfbf1", "secondaryBorderColor": "#2dd4bf", "secondaryTextColor": "#1f2d3d", "tertiaryColor": "#fef3c7", "tertiaryBorderColor": "#facc15", "tertiaryTextColor": "#1f2d3d", "lineColor": "#0066cc", "textColor": "#1f2d3d", "nodeTextColor": "#1f2d3d", "edgeLabelBackground": "#ffffff" } }}%% flowchart LR CALL["Incoming call with
United States caller ID"] SETTING{"Enable CNAM Lookup
enabled?"} LOOKUP["Query remote
CNAM database"] RESULT{"Name returned?"} NAME["Add caller name to
SIP From display name"] UNAVAILABLE["Use Unavailable as
SIP From display name"] NUMBER["Use caller ID as
SIP From display name"] LOG["Populate Source Name
in inbound call logs"] ENDPOINT["Deliver call to
SIP endpoint"] CALL --> SETTING SETTING -->|Yes| LOOKUP --> RESULT SETTING -->|No| NUMBER --> ENDPOINT RESULT -->|Yes| NAME --> LOG --> ENDPOINT RESULT -->|No| UNAVAILABLE --> ENDPOINT classDef endpoint fill:#e0f2fe,stroke:#0066cc,color:#1f2d3d,stroke-width:1.5px classDef process fill:#ccfbf1,stroke:#2dd4bf,color:#1f2d3d,stroke-width:1.5px classDef decision fill:#fef3c7,stroke:#facc15,color:#1f2d3d,stroke-width:1.5px class CALL,ENDPOINT endpoint class LOOKUP,NAME,UNAVAILABLE,NUMBER,LOG process class SETTING,RESULT decision linkStyle default stroke:#0066cc,stroke-width:1.5px ``` When **Enable CNAM Lookup** is enabled, an additional charge applies to each call from a U.S. source number. The rate is shown in the trunk settings when you enable the setting. CNAM IN charges appear in the **CNAM IN (USD)** field in [inbound call logs](../../../../logs-analytics/call-logs/inbound-logs.html#inbound-cdr-logs). ## SIP delivery DIDWW places the CNAM result in the display-name portion of the SIP `From` header. The caller ID remains in the user part of the SIP URI. | Lookup state | SIP `From` header | | --- | --- | | Lookup disabled | `From: "12899230448" ;tag=example` | | Lookup successful | `From: "KRIS TOTAL" ;tag=example` | | Lookup unsuccessful | `From: "Unavailable" ;tag=example` | In a successful result, `KRIS TOTAL` is the caller name and `15203981500` is the caller ID. The same retrieved name appears in the **Source Name** field in inbound call logs. ## Trunk Group behavior When a [Trunk Group](../../trunk-groups/index.html) contains at least one trunk with **Enable CNAM Lookup** enabled, DIDWW performs a lookup for every incoming call routed to the group. Each call from a U.S. source number incurs the CNAM lookup charge, even when the selected trunk does not have the setting enabled. The caller name is delivered only through trunks that have **Enable CNAM Lookup** enabled. Important Review every member before enabling CNAM lookup on a trunk in a Trunk Group. Enabling the setting on one member changes lookup and billing behavior for calls routed to the entire group. ## Availability and limitations - CNAM IN lookup applies to incoming calls with a United States caller ID. - CNAM lookup is also available on [phone.systems(TM) trunks](../../phone-systems-trunks/index.html). See [Additional Services](../../phone-systems-trunks/phone-systems-trunk-settings-reference.html#inbound-phone-systems-trunk-settings-additional-services) in the phone.systems(TM) trunk settings reference. - The lookup result depends on the information available from the remote CNAM database. A name is not returned for every caller ID. - CNAM IN does not verify that the calling party owns or is authorized to use the caller ID. For caller-ID authentication information, see [STIR/SHAKEN for inbound calls](stir-shaken-headers.html). - The receiving SIP system must support and preserve the display name in the SIP `From` header to present the caller name to users or applications. How the name is presented depends on the receiving system. ## Configuration reference Configure **Enable CNAM Lookup** under **Additional Services** when creating or editing an inbound SIP trunk. For the field definition and default value, see [Additional Services](../sip-trunk-settings-reference.html#inbound-sip-trunks-settings-additional-services) in the SIP trunk settings reference. To enable CNAM lookup on an existing trunk, see [Manage SIP trunks](../how-to-guides/manage-sip-trunks.html#inbound-sip-trunks-enable-cnam) or [Manage phone.systems(TM) trunks](../../phone-systems-trunks/how-to-guides/manage-phone-systems-trunks.html#inbound-phone-systems-trunks-enable-cnam). ## Related resources - [Inbound call logs](../../../../logs-analytics/call-logs/inbound-logs.html#inbound-cdr-logs) - Review the retrieved caller name and CNAM IN charge for a call. - [Caller ID and CNAM OUT](../../../outbound-trunks/caller-id-cnam-out.html) - Understand caller-name delivery for outbound calls. - [STIR/SHAKEN for inbound calls](stir-shaken-headers.html) - Understand how caller-ID authentication differs from caller-name lookup. On this page