Napster agents can now answer inbound calls over your own SIP trunk — callers reach the agent through the same phone infrastructure your business already operates. This is in addition to the existing outbound SIP and VoIP capabilities.
Napster API's SIP support is native to the Azure Portal and integrates with Microsoft Foundry, so Azure customers can activate and deploy phone-based agents without standing up new infrastructure. It's also transactable through the Microsoft Marketplace, so you can apply an existing Azure Consumption Commitment toward it or procure through an existing Microsoft partner.
What inbound SIP support does
- Answers calls placed to a phone number connected through your SIP trunk
- Holds a conversation in any of the agent's supported languages, detected automatically from the caller
- Escalates to a human staff member the moment a caller needs one, without the caller hanging up and calling back
Inbound vs. outbound
| Inbound | Outbound | |
|---|---|---|
| Who initiates | The caller dials a phone number connected to your agent | Your agent dials a phone number |
| Trigger | Caller action | Your system or workflow triggers the call |
| Use cases | Support lines, reservation lines, customer-initiated calls | Proactive outreach, callbacks, reminders |
See Outbound SIP Calls — Agent-Initiated Phone Calls for the outbound-specific setup.
Prerequisites
- An active Napster API account and a configured agent (
agentId) - A valid API key for your application
- Either an Azure subscription with access to the Napster API offer in the Microsoft Marketplace, or an existing SIP trunk/phone number from your own carrier
- Admin access to your phone system if you're connecting an existing number rather than provisioning one through Azure
Setting up an inbound SIP connection
- Activate the offer (Azure path). From the Azure Portal, locate the Napster API SaaS resource and confirm the subscription status is Succeeded with a linked SaaS subscription.
- Register a SIP connection for your agent. Use the connections endpoint with
channelTypeset tosip:POST /public/agents/{agentId}/connectionswith{"channelType": "sip"}. This is the same endpoint used forwebrtcandwebsocketconnections — only thechannelTypevalue changes. - Point your phone number at the returned SIP endpoint. Configure your carrier or SIP trunk to route inbound calls to the connection details returned by the API.
- Set escalation rules. Configure the conditions under which the agent hands the call to a human (e.g. the caller asks for a person, a confidence threshold is crossed, or a specific intent is detected).
- Test the connection. Place a test call to confirm the agent answers, responds in the expected language, and escalates correctly.
Full API reference: developers.napster.com/docs/deploying-your-omniagent/phone
Troubleshooting
Call doesn't connect / rings with no agent response
- Confirm the SIP connection was created successfully (
GET /public/agents/{agentId}/connections) and its status is active. - Confirm the phone number/trunk is correctly pointed at the SIP endpoint returned during setup.
- If this is an Azure-provisioned number, confirm the SaaS subscription is active, not just configured.
Call connects but the agent doesn't respond
- Check that the agent has an active
sipchannel configuration and not justwebrtc/websocket— channels are configured independently perchannelType. - Verify your API key and
agentIdare valid for the environment (production vs. staging) the call is routing through.
Escalation to a human doesn't trigger
- Review the escalation rule configuration for the agent and confirm the trigger condition matches what's expected.
- Confirm the destination staff member or queue is reachable.
Audio quality issues or dropped calls
- Confirm there is no SIP ALG (Application Layer Gateway) enabled on the customer's router/firewall — a common cause of corrupted call setup packets even when the trunk is configured correctly.
- Collect call logs with timestamps and the SIP response code, if available, before escalating to Engineering.