#Hello team. I am having problems with the transfer_to_number tool. I can not make it work. I wan

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gilded viperBOT
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AI-generated Answer for f3rch00361

Short answer: ElevenLabs doesn’t publish FreePBX/Asterisk–specific instructions. However, the transfer_to_number tool works when your calls run over SIP trunking and you configure either Conference transfer or SIP REFER as outlined below. If any of these prerequisites aren’t met, transfers will fail.

What to set up on the ElevenLabs side

  • Use SIP trunking for your phone number so calls between your PBX and ElevenLabs are SIP. Inbound from your PBX should target ElevenLabs’ origination URI sip:sip.rtc.elevenlabs.io:5060;transport=tcp. Signaling is TCP/TLS; media (RTP) is UDP. Allow TCP 5060 or TLS 5061 for SIP and open RTP UDP on your firewall. ElevenLabs’ SIP side runs at 48 kHz; your PBX must support or resample.

  • In your agent, add the system tool “Transfer to Human” (transfer_to_number). The tool only works on phone calls (not the chat widget).

  • Define transfer rules:

    • Transfer Type: choose Conference (default) or SIP REFER.
    • Number Type: Phone (E.164) or SIP URI.
    • Destination: E.164 phone number or a SIP URI like sip:1001@your-pbx.example.com.
    • Condition: e.g., “User explicitly asks to speak to a human.”

Choosing the right transfer method

  • SIP REFER (direct handoff): Works only when the live call itself is over SIP and your SIP trunk/PBX allows REFER. Required if you want to transfer to a SIP URI (e.g., an internal FreePBX extension or queue).
  • Conference transfer: ElevenLabs calls the destination, bridges the caller and the human, then removes the AI. Use this if REFER isn’t supported. Note that only SIP-trunked numbers can transfer to external numbers; Twilio-hosted numbers can transfer only to other Twilio numbers unless you use Twilio Elastic SIP Trunking via SIP.

Example: rule and tool call

  • Rule (in the Agent UI): Transfer Type = SIP REFER; Number Type = SIP URI; SIP URI = sip:1001@pbx.yourdomain.com; Condition = “When the user asks for a human agent.”
  • The LLM must call the tool with a transfer_number that matches a configured rule and include client/agent messages, for example:
    {
    "type": "function",
    "function": {
    "name": "transfer_to_number",
    "arguments": "{"reason":"Escalation","transfer_number":"sip:1001@pbx.yourdomain.com","client_message":"Connecting you to a human agent now.","agent_message":"Customer requested escalation to support."}"
    }
    }

Troubleshooting checklist

  • Ensure your number is connected via SIP trunking (not just the Twilio native integration if you need off‑Twilio transfers).
  • If using SIP REFER, confirm your PBX/trunk accepts REFER and that the live call leg is SIP.
  • Verify SIP/RTP networking: TCP 5060 or TLS 5061 open for SIP; RTP UDP allowed; certificates valid if using TLS; and sample-rate handling at 48 kHz.

If you need FreePBX-specific dialplan or REFER settings, they’re not covered in the ElevenLabs docs. If you can share your current SIP trunking setup (signaling transport, TLS, and whether REFER is enabled), I can cross-check it against the documented ElevenLabs requirements above.

empty moat
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From which IP addresses Will i receive the call?

gilded viperBOT
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AI-generated Answer for f3rch00361

Short answer:

  • SIP trunking: SIP INVITEs to your PBX come from sip.rtc.elevenlabs.io, which sits behind multiple SIP servers. Source IPs vary; do not expect a single fixed IP. If your security policy requires allowlisting, we offer an Enterprise “static IP SIP servers” option that uses a dedicated /24 block you must allowlist; region‑specific static endpoints exist for EU and India. RTP media uses dynamic IPs/ports and cannot be reliably allowlisted.

  • Twilio integration: If your transfers run through a Twilio-connected number, the outbound leg is placed via Twilio. In that case, calls will originate from Twilio’s infrastructure (refer to Twilio’s published IP ranges).

Notes:

  • For SIP, our load-balanced architecture means SIP requests may come from different IPs unless you’re on the Enterprise static-IP option.
  • Media (RTP) flows over UDP with dynamic ports (typically 10000–60000); don’t lock this to fixed IPs.

If you need static allowlistable IPs, let me know your region (US/EU/IN) and whether you’re using SIP trunking directly or Twilio, and I’ll point you to the correct Enterprise setup.

empty moat
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I am using SIP trunking. I do not know which is my region. My IP address is 200.108.112.35

gilded viperBOT
#
AI-generated Answer for f3rch00361

Short answer: with ElevenLabs SIP trunking you don’t need to pick an “ElevenLabs region.” Use the global SIP endpoint; source IPs are dynamic unless you enable the enterprise static-IP option.

Details:

  • SIP endpoint: inbound INVITEs to ElevenLabs are routed to sip.rtc.elevenlabs.io (TCP 5060 by default; TLS on 5061 if enabled). This URI is auto-populated when you import a SIP trunk. (elevenlabs.io)
  • Source IPs: traffic comes from multiple SIP servers behind the sip.rtc.elevenlabs.io load balancer, so requests can originate from different IPs. If you must IP-allowlist, use the enterprise “Static IP SIP Servers” option, which uses a single /24 block across US/EU/IN; you must allowlist the entire /24. For strict regional residency, use the static endpoints sip-static.rtc.eu.residency.elevenlabs.io or sip-static.rtc.in.residency.elevenlabs.io; per‑region specific IP lists aren’t available. (elevenlabs.io)
  • Signaling vs media: SIP signaling supports TCP or TLS (UDP signaling isn’t supported). RTP media flows over UDP; ensure your firewall/NAT allows the RTP range (typically UDP 10000–60000). (elevenlabs.io)
  • “SIP Region” in provider portals: if your SIP carrier (e.g., Telnyx) asks you to choose a region, that choice is on the carrier side (pick the POP closest to your PBX). It doesn’t change the ElevenLabs endpoint, which remains sip.rtc.elevenlabs.io. (elevenlabs.io)

We can’t determine your carrier’s “region” from your public IP (200.108.112.35). If you need static IPs or data‑residency routing, please contact ElevenLabs to enable the static-IP SIP option. (elevenlabs.io)

Sources:
SIP trunking
SIP trunking | ElevenLabs Documentation
SIP trunking | ElevenLabs Documentation
Telnyx SIP trunking | ElevenLabs Documentation
SIP trunking | ElevenLabs Documentation

empty moat
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Where do I enable the Enterprise static-ip option?

gilded viperBOT
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AI-generated Answer for f3rch00361

It isn’t a self‑serve toggle. Enterprise static‑IP SIP servers are enabled by ElevenLabs for Enterprise accounts. Per our SIP trunking docs, you need to contact your account representative (or contact sales) to have it provisioned. Once enabled, you’ll point your trunk to the static SIP endpoint (e.g., sip-static.rtc.eu.residency.elevenlabs.io or sip-static.rtc.in.residency.elevenlabs.io for regional residency) and allowlist the provided /24 block. (elevenlabs.io)

Sources:
SIP trunking | ElevenLabs Documentation

grizzled lagoon
#

@empty moat Did you find solution?