How I Built a Self-Hosted PBX With Asterisk and VAPI for 6 Business Phone Lines

Six businesses. Six phone numbers. One server. Zero monthly phone system fees.

Here is exactly how I built it.

The Problem

Every business needs a phone line. Business phone systems charge $30 to $80 per line per month. For six lines that is $180 to $480 every month just to receive calls.

I refused to pay that.

The Stack

Asterisk 18.10 — open-source PBX running on lb-telecom-01 (Vultr Dallas VPS at 45.32.198.24)
VoIP.ms — SIP trunk provider, KYC approved, six 832-area-code DIDs at $4.95/month each
VAPI — AI voice agent layer sitting in front of Asterisk

Total monthly cost: $29.70 for six lines. Not per line. Total.

The DIDs

Six numbers provisioned on Flat Rate through dallas1.voip.ms:

1315 — Load Bearing Capital
1316 — Load Bearing Demo
1317 — Quiet Hours Valet
1318 — Luchin Credit Repair
1319 — Petroleum Noir
1321 — Load Bearing Detailing

How VAPI Connects

VAPI sits as the public-facing layer. Calls come in, VAPI answers with a brand-specific AI voice agent, qualifies the caller, and routes or logs based on intent.

Asteisk handles the SIP registration and trunk. VAPI handles the intelligence.

The PJSIP trunk is registered to account 528502 on VoIP.ms.