> ## Documentation Index
> Fetch the complete documentation index at: https://documentation.uponai.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Receive Calls
> Set up your phone number to receive inbound calls with a bound voice agent.
## Bind Voice Agents
Only when you bind agents to a number will the number be able to receive and make calls.
* You can assign different inbound and outbound agents to the same number.
* Leave an agent unset to disable inbound or outbound (e.g. if you're doing outbound only and don't want callbacks, leave `inbound_agent_id` unset).
* After binding an inbound agent, your number is ready to receive calls immediately.
## A/B Testing
See [A/B Testing](/Deploy/ab-testing) to route a percentage of inbound calls to different agents.
## Inbound Call Webhook
Often you'll want to use different agents to handle inbound calls on the same number, provide dynamic variables, or customize other call fields per-call. Use the **Inbound Call Webhook** to handle this.
Read more at the Inbound Call Webhook documentation.
## Inbound Custom SIP Headers
You can use custom SIP headers to pre-set dynamic variables for a call.
UponAI extracts any header starting with `sip.h.x-`, along with common SIP headers like `Diversion`, `History-Info`, `User-To-User`, and `P-Asserted-Identity`, and converts each into a dynamic variable by stripping the `sip.h.` prefix.
**Examples:**
* `sip.h.x-caller: abc` → `x-caller: abc`
* `sip.h.p-asserted-identity: +12345678910` → `p-asserted-identity: +12345678910`
* `sip.h.diversion: ;privacy=off;reason=no-answer` → `diversion: ;privacy=off;reason=no-answer`
## Get Call Details
After a call completes, you can retrieve full call information:
Use the **Get Call API** to retrieve the transcript, recording, latency tracking, and more.
Set up webhooks to receive real-time updates when a call is initiated, ends, and is analyzed. Read more at the Call Webhook Guide.