SIP Headers and Workflows
# support
w
Hello guys, do we know if workflows support SIP headers ? Because it seems that only the assistant is able to fill the dynamic variables based on the SIP headers And the workflows do not 76e0f5fb-8340-43d3-9557-74e8c9819b01
c
Workflows do not natively support SIP headers for dynamic variables only Assistants can auto-fill them via
assistantOverrides.variableValues
, so to use SIP headers in a Workflow, you must route the call through an Assistant webhook that injects the variables.. [https://docs.vapi.ai/advanced/sip](https://docs.vapi.ai/advanced/sip?utm_source=chatgpt.com) [https://docs.vapi.ai/workflows/overview](https://docs.vapi.ai/workflows/overview?utm_source=chatgpt.com)
w
Ok thank you very much, let me see if we can integrate this in our work flow
When doing the SIP integration however
Given this PCAP
I see the following
INVITE sip:prod-vici-auto-screener-sip@sip.vapi.ai SIP/2.0 Via: SIP/2.0/UDP 207.188.10.143:5060;branch=z9hG4bK7d60ec91;rport Max-Forwards: 70 From: "8169335555" ;tag=as7fe91873 To: Contact: Call-ID: 155fe60759e312f760012948388e5cf0@sip.vapi.ai CSeq: 102 INVITE User-Agent: Asterisk PBX 18.26.2-vici Date: Thu, 24 Jul 2025 16:57:30 GMT Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH, MESSAGE Supported: replaces, timer X-Lead-ID: 96458322 X-Lead-Type: AUTO X-Model: Toyota X-Make: Corolla X-Year: 2021 P-Asserted-Identity: "8169335555" Content-Type: application/sdp Content-Length: 261
And the variable customer.phone NOT being set
@Shubham Bajaj call id
c
Vapi workflows don’t auto-populate [customer.phone](http://customer.phone) from SIP INVITE headers, only Assistants do via assistantOverrides, so to set the caller’s number like From: or X-Lead-\* headers, you’ll have to handle it in an Assistant webhook and pass it manually as a variable..
w
Thanks
Can you further elaborate?
? TY
c
Hello, Thanks for patiently waiting. Vapi workflows currently don’t auto-populate the
customer.phone
field from the SIP INVITE headers. This behavior is only available when using Assistants, since they can parse those headers through
assistantOverrides
. If you need to capture the caller’s number (for example, from the
From:
header or custom headers like
X-Lead-*
), the way to handle this is through an Assistant webhook. In the webhook, you can extract the caller information from the SIP INVITE headers and then pass it manually into your workflow as a variable. In other words: - Workflows = no automatic mapping from SIP headers →
customer.phone
. - Assistants = can override and pull that info with
assistantOverrides
. - Solution = use a webhook to grab the header data yourself and inject it into the workflow. Let us know if you need further assistance.
d
Hello, can you help me and explain how to create a webhook to grab the header data yourself and inject it into the workflow?
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