Troubleshoot inbound route with asterisk based magnus billing portal

I'm seeking an expert with a deep understanding of Asterisk and Magnus Billing Portal to resolve a critical issue we're facing. Our system currently fails to establish connections for incoming calls right at the beginning of the call process. This persistent problem is resulting in missed communications and potential business losses.

Ideal Candidate:
- Proficient with Asterisk PBX systems
- Experienced with Magnus Billing setups
- Strong diagnostic and problem-solving skills

Scope of Work:
- Analyze and pinpoint the cause of the call connection failure
- Troubleshoot and fix the routing issue to ensure call connectivity
- Test and confirm that the issue is fully resolved

Timeline & Communication:
- Immediate availability preferred
- Consistent updates required

Let's restore seamless telephony functionality together!