Update sip-trunk.mdx

sahilsuman933 · web-flow · commit 71043cbc9242 · 2025-07-02T04:25:25.000+05:30
diff --git a/fern/advanced/sip/sip-trunk.mdx b/fern/advanced/sip/sip-trunk.mdx
@@ -112,6 +112,9 @@ Vapi supports multiple SIP trunk configurations, including:
 
     Example: `sip:15557654321@sip.zadarma.com`
 
+Note: Certain providers require phone numbers to be formatted in the proper E.164 standard. For example, the transfer URI should appear as: `sip:+15557654321@sip.zadarma.com`.
+﻿
+
     Example tool configuration required for SIP REFER:
     ```json
     {

Original file line number	Diff line number	Diff line change
`@@ -112,6 +112,9 @@ Vapi supports multiple SIP trunk configurations, including:`
`112`	`112`
`113`	`113`	Example: `sip:15557654321@sip.zadarma.com`
`114`	`114`
	`115`	+Note: Certain providers require phone numbers to be formatted in the proper E.164 standard. For example, the transfer URI should appear as: `sip:+15557654321@sip.zadarma.com`.
	`116`	`+`
	`117`	`+`
`115`	`118`	`Example tool configuration required for SIP REFER:`
`116`	`119`	```json
`117`	`120`	`{`