Transfer call failing with 403 / "Not enough customer balance" – worked for 6 weeks, suddenly broken

Support Help
1

Hi Retell Team,

We are experiencing the same issue reported in threads /2834 and /2854.
Our transfer_call functions stopped working a few days ago. They had
been working in production without issues for the past 6 weeks.

Details:

  • Tools affected: derivar_recepcion_1 and derivar_recepcion_2
  • Failing call ID: call_2776107d6476e00a8d3932b73d0
  • Agent ID: agent_e57e47102383c6c148c43aafc3
  • Inbound number: +34967797032 (Spain, Custom telephony)
  • Transfer destinations: +34967134095 and second reception line, both
    Spain fixed numbers from the same Movistar carrier as the inbound

SIP error from the log:
SIP status code: 403
SIP error category: telephony_provider_permission_denied
Error: sip status: 403: Not enough customer balance

What we confirmed:

  • Tool is invoked correctly in logs
  • No changes on our side (workflow, prompt, agent, destination numbers)
  • Inbound calls work normally
  • All other tools (webhook-based) work normally
  • Account billing is active (Pay As You Go, post-paid, monthly charge on day 22)
  • Issue is constant, not intermittent

This is a production system serving a medical clinic, so it’s urgent.
Could you please investigate on your side and confirm whether this is
related to the same incident as threads 2834 and 2854?

Thanks.

2

Hi @infoai Checking with the team.

3

Hey @infoai This error is coming from your provider not us , you need to check his balance on phone provider. Thank You