Hey team — I’m trying to set up outbound calling in Vapi using FlyNumber, which uses DIDWW phone.systems for SIP termination. Goal: Outbound calls from Vapi through phone.systems (inbound not needed). Carrier details (phone.systems): Termination Gateway: UDP IPv4 44.229.228.186:5060 Auth user: 100018908 (+ password configured in phone.systems) Codecs allowed: PCMU, PCMA, telephone-event phone.systems/FlyNumber support says calls fail because of leading “+” in E.164. We set DST rewrite in phone.systems gateway/route: ^\+([0-9]+)$ -> \1 to strip the plus. Problem: Outbound attempts return SIP 480 Temporarily Unavailable phone.systems call logs show Route “-” for failed attempts. Questions: What’s the correct Vapi BYO SIP trunk configuration for phone.systems termination? Should Vapi be sending E.164 with + or without — and is there a Vapi setting to control it (or should we rely on phone.systems rewrite)? Any common causes of 480 with BYO SIP trunks (auth, From/CLI, codecs, transport)? If it helps I can share sanitized screenshots of the phone.systems gateway + termination route settings.

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To resolve the leading "+" issue for outbound calls via phone.systems, set

outboundLeadingPlusEnabled

to

false

in your Vapi SIP trunk credential configuration. Here’s an example payload:

json
{
  "provider": "byo-sip-trunk",
  "name": "PhoneSystems Trunk",
  "gateways": [{
    "ip": "44.229.228.186",
    "port": 5060,
    "outboundEnabled": true,
    "inboundEnabled": false
  }],
  "outboundLeadingPlusEnabled": false,
  "outboundAuthenticationPlan": {
    "authUsername": "100018908",
    "authPassword": "YOUR_SIP_PASSWORD"
  }
}

This will ensure Vapi sends numbers without the "+" prefix, matching phone.systems requirements. For more details, see the [Vapi SIP trunk documentation](https://docs.vapi.ai/advanced/sip/sip-trunk). Source: - [Vapi SIP trunk documentation](https://docs.vapi.ai/advanced/sip/sip-trunk)

This looks like a SIP trunk config mismatch rather than just the “+” issue. I can help you get it working typically 480 errors here come from auth/CLI mismatch, incorrect From header, or codec/transport settings not aligning with phone.systems. Vapi usually sends E.164 with “+”, so the rewrite should work, but we’ll want to confirm the trunk config and routing rules. Happy to review your Vapi + phone.systems setup and fix the outbound flow quickly @Icydomo

i have to be honest with u i am totally ignorant here i just started my bussines and im running this alone and fly number has a phone system of didww wich is manual u have to manually create the sip account and the outbonad part in trunks im sure it has been something wron for me and im also using vapi agent wich is very helpful so yes i need help if u can help me manage this it would be very good for me since this week im about to run a test with a clinic wich is waiting me from 3 weeks

Let's connect @Icydomo

ok

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