SIP Trunking Savings: Replace PRI Lines and Save 40-60% on Voice

SpendWire Team•3 min read•November 11, 2026

PRI lines cost $300-500 each. SIP trunks deliver the same capacity for $15-25 per channel. The math is not close.

If your enterprise is still paying for PRI lines, you are overpaying for voice by 40-60%. SIP trunking delivers the same call capacity over your existing internet connection at a fraction of the cost. The technology is mature, the quality is excellent, and the savings are immediate.

PRI vs SIP: The Numbers

PRI Line Costs

A single PRI delivers 23 simultaneous voice channels. Typical pricing:

PRI circuit: $300-500 per month

Cost per channel: $13-22 per channel

Installation: $500-1,500 one-time

Long distance: $0.02-0.05 per minute on top of the circuit cost

SIP Trunk Costs

SIP trunks are purchased per channel with no physical circuit required:

Per channel: $15-25 per month (includes unlimited local and LD in most plans)

No installation fee for most providers

No long distance charges on metered plans: $0.01-0.02 per minute

Burst capacity: add channels instantly during peak periods

Real-World Example

A company running 10 PRI lines (230 voice channels):

PRI cost: $4,000 per month + $500 long distance = $4,500 per month

SIP equivalent (230 channels at $18): $4,140 per month, but they only need 150 channels at peak

Right-sized SIP: 150 channels at $18 = $2,700 per month

Annual savings: $21,600. And that is a conservative estimate.

Migration Considerations

Keep Your Numbers

Number porting from PRI to SIP is standard. Every SIP provider handles this. The process takes 10-15 business days per batch. Plan for a 2-4 week porting timeline per location.

Bandwidth Requirements

Each SIP call uses approximately 85-100 Kbps. For 150 simultaneous calls, you need about 15 Mbps of dedicated bandwidth. If your internet circuit is shared with data traffic, implement Quality of Service to prioritize voice packets.

E911 Compliance

SIP trunking requires Registered Location (RL) entries for every physical location where calls originate. Your SIP provider must support E911, and you must keep location records current. This is a legal requirement, not optional.

Fax Lines

Fax over SIP (T.38) works but is less reliable than traditional fax. For mission-critical fax (healthcare, legal), consider keeping 1-2 analog lines or switching to eFax services.

Top SIP Providers for Enterprise

Lumen (CenturyLink): strong for companies already on their network

Windstream: competitive pricing, good Midwest and Southeast coverage

Comcast Business: solid option if they provide your internet

Bandwidth.com: carrier-grade SIP, excellent API

Twilio: usage-based pricing, great for variable call volumes

When to Migrate

If your PRI contract is expiring in the next 12 months, start planning now. If you are mid-contract, calculate whether early termination fees are less than the savings over the remaining term. SpendWire can model both scenarios and show you the breakeven point.

The question is not whether to migrate from PRI to SIP. The question is how much money you are losing every month that you wait.

SIP trunkingPRIvoiceVoIPcost savings