I connected Zadarma SIP to vapi, following all of the instructions here: https://docs.vapi.ai/advanced/sip/zadarma As at test, when i tested with outbound calls via api and a direct number, i got this error: An error occurred in this call: call.in-progress.error-providerfault-outbound-sip-503-service-unavailable. Now when i have the client perform an inbound call whereby he called the virtual number that was created, it worked successfully. I wish i knew where this issue is coming from, looking forward to your response.

call_id pls

Helloo

Hey, can you book a quick call and we can discuss it over there?