Outbound calls via VoIP.ms SIP trunk failing with: call.in-progress.error-providerfault-outbound-sip-503-service-unavailable Your own Wiki acknowledges: "Outbound calls from Vapi are currently not guaranteed" This has been a known issue - when will it be fixed? #sip-trunk #vapi https://cdn.discordapp.com/attachments/1461445004680626308/1461445005640990843/Screenshot_2026-01-15_143801.png?ex=698054f9&is=697f0379&hm=22f980f71c332bb1554b6c873bd7353e6105adca7ed6512ba3146fb8498c6952&

I hear you—it’s really frustrating when outbound calls hit that 503 error and disrupt your workflow. We know outbound SIP via Vapi isn’t fully reliable yet and are actively working on fixing it. Can you share how many calls this affects for you and how critical they are? @TheMadHitter

Well it's really critical because I'm trying to create something for a mortgage broker. I didn't manage to figure out a way around it as a fallback. Just testing to see if that option works at the moment.

Got it, I completely understand how critical this is, especially for a mortgage broker workflow where every call matters. While outbound SIP isn’t fully reliable at the moment, there are a few strategies we can explore to make things more robust like fallback routing via PSTN, pre-validating numbers, or batching critical calls differently. If you want, we can go over these approaches privately and map out a method that works reliably for your setup. @TheMadHitter

For now I think I have it figured out. Thanks for reaching out. Infact calls actually are going out almost instantly with what I did. Maybe just an accident but it's working

Hi @TheMadHitter, I am glad that you were able to resolve your issue. If you face any further issues, feel free to reach out.