A Cost-Focused Breakdown From the Telecom Specialists at Affiliated Communications

Quick Answer

For most mid-sized businesses, SIP trunking costs 30 to 60 percent less than equivalent PRI service. The savings come from lower per-channel costs, eliminated long-distance charges, no need for dedicated copper circuits, and the ability to right-size capacity based on actual usage. PRI still makes sense in specific cases, but the cost gap has widened to the point where SIP is the default choice for new deployments and a strong upgrade case for businesses still on PRI.

What PRI Actually Is

Primary Rate Interface, or PRI, is a digital telephone service delivered over dedicated T1 circuits. Each PRI provides 23 voice channels (sometimes 30 in international configurations) plus one signaling channel. PRIs have been the workhorse of business telephony for decades, especially for organizations with more than 10 to 15 simultaneous calls.

Practically, a PRI looks like a digital phone line that connects your on-premise PBX to the public phone network. The carrier provides the circuit, you pay a monthly fee plus usage charges, and your business gets predictable voice service. PRIs are reliable, well-understood, and supported by virtually every PBX platform.

They’re also expensive, inflexible, and built on technology that the major carriers are actively retiring.

What SIP Trunking Actually Is

SIP (Session Initiation Protocol) trunking delivers the same voice service as PRI but over the internet rather than dedicated telephone circuits. Your PBX connects to a SIP trunking provider through your existing internet connection, and voice calls travel as data.

Functionally, SIP trunks do everything PRIs do: connect your business phone system to the public phone network, support inbound and outbound calls, deliver caller ID, and handle direct inward dialing (DID) numbers. The difference is the delivery mechanism—and the economics that come with it.

Affiliated Communications provides SIP trunk services for businesses that want to keep their existing PBX while modernizing the carrier connection. It’s one of the most common upgrades we deploy, because the savings are immediate and the disruption is minimal.

The Real Cost Comparison

PRI Cost Structure

A typical PRI in North Texas in 2026 runs $400 to $700 per month for the circuit, with per-channel costs effectively in the $17 to $30 range. Long-distance calls are billed separately, often at five to ten cents per minute. Additional PRIs for capacity scale linearly—need 50 simultaneous calls? You’re paying for at least two PRIs whether you use the full capacity or not.

On top of the monthly circuit costs, businesses often pay maintenance fees, installation charges for new lines, and feature add-ons for things like caller ID and call forwarding. Total monthly costs for a business needing 40 to 60 channels frequently exceed $1,500 per month before usage.

SIP Trunking Cost Structure

SIP trunks are priced per channel, with per-channel costs in 2026 typically ranging from $10 to $20 depending on volume and provider. Most SIP services include unlimited domestic long distance, which eliminates per-minute charges that add up quickly on PRIs. Capacity scales smoothly—you pay for what you use rather than buying capacity in 23-channel blocks.

For the same 40 to 60 channel business, monthly SIP costs typically run $500 to $1,200—a 40 to 60 percent reduction compared to equivalent PRI service. The savings come without any reduction in features or reliability when SIP is properly deployed.

Real-World Example

A 75-employee professional services firm running two PRIs (46 channels) was paying $1,800 monthly for circuits plus another $400 in long-distance charges, totaling $26,400 annually. After switching to SIP trunking sized for their actual usage (35 channels), monthly costs dropped to $700 with unlimited long distance included—total annual cost $8,400. The first-year savings exceeded $18,000, with the same call quality and the same on-premise PBX. This kind of math drives most of the SIP trunking deployments we handle.

Beyond Cost: The Other Advantages

Scalability

SIP trunks scale in single-channel increments. Need to add five channels for a busy season? Done in hours. PRIs scale in 23-channel jumps with installation timelines measured in weeks. For businesses with seasonal call patterns, growth plans, or fluctuating capacity needs, SIP’s scalability is a major operational advantage.

Number Portability and Geographic Flexibility

SIP trunks aren’t tied to a physical location. A business in McKinney can have phone numbers in San Antonio, Houston, Denver, and Atlanta on the same SIP trunk, with calls routed to whatever destination makes sense. PRIs are tied to the physical circuit termination, which limits flexibility.

Disaster Recovery

When your office loses power or internet, SIP trunks can reroute calls automatically to mobile devices, alternate offices, or backup destinations. PRIs go down with the physical infrastructure they’re connected to. For business continuity, SIP’s flexibility is meaningfully better.

Redundancy

SIP trunks can be delivered over multiple internet connections from different carriers, providing redundancy that single-PRI deployments simply can’t match. Combined with SD-WAN, SIP trunks can deliver voice quality and reliability that exceeds traditional PRI.

When PRI Still Makes Sense

Despite the cost and flexibility advantages of SIP, PRI is still the right choice in certain situations:

Locations with genuinely unreliable broadband and no fiber availability
Environments where regulatory requirements mandate dedicated circuits
Organizations with PRI contracts that have significant remaining term
Very small businesses where a single PRI is significantly cheaper than the equivalent SIP minimum
Specialized integrations that require PRI-specific signaling

For most mid-sized businesses, none of these conditions apply. The case for SIP is strong enough that PRI defaults are increasingly difficult to justify.

The Bigger Picture: PRI Is Being Phased Out

This is the consideration that surprises business owners who haven’t been tracking carrier announcements. The major carriers are actively retiring PRI service and the underlying TDM infrastructure that supports it. AT&T, Verizon, and most regional carriers have published end-of-life timelines for PRI, with formal retirement dates ranging from 2027 to 2030 depending on the market.

What this means in practical terms: businesses staying on PRI face rising costs as carriers raise rates to encourage migration, declining service quality as carriers reduce investment in legacy infrastructure, and an eventual forced migration when their PRI service is decommissioned. Moving to SIP on your timeline is dramatically better than being forced to migrate on the carrier’s timeline.

Implementation: What a SIP Migration Looks Like

For a business with an existing PBX, migrating from PRI to SIP is one of the simplest telecom projects we handle. The general process:

Network assessment to confirm internet capacity and quality
PBX compatibility check (most modern PBXs support SIP natively)
Right-sizing the channel count based on actual call patterns
Number porting from the existing PRI provider
Cutover, often scheduled for a weekend or evening to minimize impact
Decommissioning of the PRI circuits

Total project timeline for a mid-sized business is typically four to eight weeks, with the actual cutover taking a few hours. The PBX itself stays in place, so users see no change in their phones, extensions, or workflows.

SIP Trunking and SD-WAN

SIP trunks ride on your internet connection, which means the quality and reliability of that connection directly affects voice quality. For businesses serious about SIP, we typically recommend deploying SD-WAN alongside—a network technology that prioritizes voice traffic, manages bandwidth dynamically, and provides automatic failover across multiple internet connections.

SD-WAN essentially eliminates the reliability concerns that used to push businesses toward PRI. With SD-WAN, SIP voice can match or exceed PRI quality and uptime, at a fraction of the cost. Affiliated Communications deploys SD-WAN as part of SIP migrations whenever the business case supports it.

How to Evaluate the Switch for Your Business

If you’re on PRI today, the question isn’t whether to move to SIP—it’s when and how. Use this framework to evaluate timing:

Move Now If:

Your PRI contract is up for renewal in the next 12 months
You’re paying $1,000+ monthly for PRI service
You have decent broadband (fiber or business cable) at your location
Your PBX supports SIP (most platforms from the last 10 years do)
You’re experiencing capacity constraints during peak periods

Move Within 12 Months If:

Your PRI contract has 12 to 24 months remaining
You’re planning network or infrastructure changes
Your carrier has notified you of PRI retirement timelines

Consider Hybrid If:

You operate from multiple sites with different connectivity profiles
Some locations have excellent broadband and others don’t
You want to test SIP at smaller sites before migrating headquarters

Where Affiliated Communications Fits

We’ve been deploying SIP trunk services across North Texas for over a decade. Our team handles network assessment, PBX compatibility verification, number porting, cutover coordination, and ongoing support. Because we’re vendor-neutral, we work with whatever PBX you have—Mitel, Avaya, or any other major platform—and we deliver SIP trunks through our own infrastructure or through carrier partnerships, depending on what fits your situation.

If you’d like a complimentary review of your current telecom invoices to see what SIP could save your business, contact our team to schedule a consultation. Our bill review process typically identifies 30 to 50 percent savings opportunities for businesses still running PRI.

Frequently Asked Questions

How much can my business actually save by switching from PRI to SIP?

Most mid-sized businesses see savings of 30 to 60 percent on monthly voice costs after switching from PRI to SIP. For a business spending $1,500 per month on PRI, that’s typically $5,000 to $10,000 in annual savings. Larger organizations see proportionally larger savings.

Will SIP voice quality be as good as PRI?

With proper deployment—adequate bandwidth, quality-of-service configuration, and ideally SD-WAN—SIP voice quality matches or exceeds PRI. The technology has matured significantly, and modern SIP deployments routinely deliver call quality indistinguishable from traditional PRI.

Do I need to replace my PBX to switch to SIP?

Usually not. Most PBX platforms from the last 10 years support SIP natively or with a software update. Mitel, Avaya, and other major systems work well with SIP trunking. Our compatibility assessment confirms this before any migration begins.

What happens to my phone numbers when I switch?

All existing numbers port to the new SIP service. Number porting is coordinated between your old carrier and the new SIP provider, with the actual port typically scheduled for after-hours to minimize disruption. Your customers continue reaching you at the same numbers throughout the transition.

How long does PRI-to-SIP migration take?

For a mid-sized business, four to eight weeks from project kickoff to final cutover. The actual cutover itself takes a few hours, usually scheduled for a weekend or evening. Number porting timelines are the biggest variable—typically 10 to 30 business days controlled by the losing carrier.

What if my internet goes down? Don’t I lose phone service?

Well-designed SIP deployments include automatic failover to backup internet connections, mobile devices, or alternate locations. With SD-WAN, the failover is seamless—calls in progress can continue uninterrupted. This actually makes SIP more resilient than PRI in many scenarios, since PRI goes down with the local circuit and SIP can fail over to anywhere.

Is the major carrier PRI retirement timeline real?

Yes. AT&T, Verizon, and most regional carriers have published end-of-life timelines for PRI service. Specific dates vary by market, but the direction is clear. Migrating on your timeline—while you have leverage and time to plan—is significantly better than waiting for a forced migration when service is decommissioned.

SIP Trunking vs. PRI Lines: What’s the Real Cost Difference for a Mid-Sized Business?