SIP trunking vs PRI, when to switch and savings math

Q: Do we have to replace every handset?

Often no. Gateways and SIP adapters can bridge legacy phones, though replacing very old handsets is usually cheaper over 24–36 months due to support and security updates.

Q: How long does number porting take in Canada?

Simple ports often complete in a few business days; complex multi-carrier or geographic splits can take longer. Port in small batches and keep a rollback plan.

Q: Can calls continue during an internet outage?

Yes, with a hybrid design: keep a PRI for essential lines, or configure local survivability and automatic fallback to LTE or secondary ISP. Test the failover behavior before cutover.

Q: What about emergency calling location accuracy?

You must keep service addresses up to date and test 9-1-1 behavior. CRTC provides VoIP 9-1-1 guidance and NG9-1-1 transition notes; follow those when you change service models.

September 30, 2025

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Meta description: Compare SIP trunking and PRI for multi-site Canadian businesses. Learn when to switch, a compact savings example, migration checklist, and compliance notes.

Last reviewed: September 30, 2025

Hook: The phone in the front lobby drops calls on Friday lunch. The network team blames the internet. The telco bill still shows multiple legacy PRIs that were never fully used. You can either pay to keep aging circuits or plan a migration that cuts monthly costs and restores control.

TL;DR: For most Canadian businesses with reliable internet, SIP trunking replaces PRI with lower monthly costs, faster rollout, and easier scaling. Keep PRI when you need a single-circuit physical failover, have poor WANs, or strict on-prem regulatory controls. Expect real savings when you consolidate multiple PRIs, reduce per-channel fees, and retire local telco hardware; run a 12–36 month TCO to see the outcome. This post shows a compact decision matrix, a sample savings calculation with assumptions, a 30-day pilot runbook, and Canada-specific compliance notes.

Buyer situation	Best fit	Typical cost pattern	Time to roll
Single-site, poor internet	PRI or hybrid	Higher fixed monthly, low variable	2–6 weeks (circuit delivery)
Multi-site (3+), managed WAN	SIP trunking (consolidated)	Lower per-channel, OPEX, scale by concurrency	2–8 weeks (pilot + cutover)
Contact centre, heavy concurrent calls	SIP trunking (capacity pools)	Lower 36-month cost, flexible channels	4–10 weeks (SBC + QoS prep)

Image alt text suggestion: “Comparison matrix: SIP trunking vs PRI showing fit, cost pattern, and rollout time.”

Key takeaways

Pick SIP when you have reliable internet and want flexible, lower-per-channel costs.
Keep or phase PRI when the site has no redundant internet or strict on-prem constraints.
Check NG9-1-1 and provincial privacy rules during design and porting. 9-1-1 obligations for VoIP (CRTC).
Do a short pilot: measure MOS, jitter, and packet loss before you cut number porting.
Run a 36-month TCO that includes SBC, handsets, carrier fees, and potential early termination charges.

What is SIP trunking and what is PRI?

SIP trunking is a software-defined method of carrying voice across an IP network. It uses session initiation protocol to establish concurrent calls that scale up or down as you need. SIP often bills by concurrent channels or pooled capacity and relies on internet or private IP links.

PRI (Primary Rate Interface) is a dedicated physical telco circuit that provides a fixed number of channels—23 concurrent calls on a North American T1 or 30 on an E1 regionally. A PRI is predictable and physically isolated from your data network, but it is less flexible and often costs more as you add locations.

Our POV: SIP is a platform model. PRI is a circuit model. Choose based on failure modes, WAN health, and total cost of ownership, not marketing claims.

How to decide: the short checklist

Start with three checks. If you answer yes to most, SIP is likely the better path.

Do you have symmetric business internet with consistent latency and packet loss under 1 percent during peak? (If not, fix or add failover.)
Do you need flexible scaling across sites or a capacity pool for contact centres?
Can you meet emergency calling and location accuracy requirements for your province?

Assumes a mid-market WAN and standard codecs. If any of the checks fail, plan a hybrid design: keep a PRI as local survivability while migrating voice to SIP at other sites.

Pros and cons: SIP trunking vs PRI

Here’s a compact list you can quote in procurement evaluations.

SIP – Pros: Scalability, lower per-channel cost, faster provisioning, centralised billing, easier disaster recovery via routing.
SIP – Cons: Depends on internet; requires SBCs, QoS, and sometimes new firewall rules.
PRI – Pros: Predictable circuit-level reliability, simple emergency behaviour on legacy networks, no SIP signaling complexity.
PRI – Cons: Fixed capacity, higher incremental cost to add channels, longer lead time for circuits, aging availability in some exchanges.

Image alt text suggestion: “Two-column list comparing SIP trunking benefits and PRI benefits for procurement teams.”

Savings math: a concrete example (labelled assumptions)

Math works only when you state assumptions. This is an example you can copy into a spreadsheet and replace numbers with your vendor quotes.

Assumptions (example) — labelled and conservative:

One site with 30 concurrent calls typical at peak.
PRI: a single T1/PRI (23 channels) plus a second T1 (to reach 30), monthly PRI circuit cost = CAD 450 per T1; porting/termination negligible for simplicity.
SIP: carrier charges CAD 25 per concurrent channel/month or a pooled plan priced at CAD 650/month for 30 channels. SBC appliance amortized at CAD 3000 one-time or CAD 100/month over 36 months. Business internet already in place; incremental bandwidth and QoS cost = CAD 50/month.
One-time migration labour (config, test, porting) = CAD 1,500.

36-month cost — PRI example

Monthly circuits: 2 x CAD 450 = CAD 900/month → 36 months = CAD 32,400
One-time migration/termination: CAD 1,500
Total 36-month PRI cost = CAD 33,900

36-month cost — SIP example

Monthly pooled SIP: CAD 650/month → 36 months = CAD 23,400
SBC amortized: CAD 100/month → 36 months = CAD 3,600
Bandwidth increment: CAD 50/month → 36 months = CAD 1,800
One-time migration labour: CAD 1,500
Total 36-month SIP cost = CAD 30,300

Result: In this example, SIP saves CAD 3,600 over 36 months — about 11 percent. Change the per-channel SIP price, SBC model, or circuit cost and the outcome can flip. For multi-site consolidations the savings grow because you retire multiple PRIs and centralize capacity.

Method note: This is an illustrative example. Replace prices with your carrier quotes, include taxes and emergency-service surcharges, and add early-termination or equipment buyout charges when present. For contact centres, model peak concurrency and trunk blocking carefully.

Hidden costs and traps to watch

Emergency calling location accuracy—update and test service addresses. See CRTC guidance for VoIP 9-1-1 obligations. 9-1-1 obligations for VoIP (CRTC).
Carrier fees and regulatory surcharges can add 10–30% to line items. Ask for a fully-burdened quote.
SBC licensing and high-availability pairs are often overlooked. Plan for two if you need site survivability.
Legacy devices: elevators, alarms, and faxes may need gateways or replacement. Validate every analog device before cutting circuits.
Network readiness: if packet loss or jitter exceed targets, you must invest in QoS, VLANs, or a second ISP link.

Implementation path: a low-risk 30-day pilot

We recommend a controlled pilot before full cutover. This 30-day path minimizes business disruption and gives measurable results.

Week 0: Inventory — list numbers, PRI channels, fax/elevator lines, and call-flow rules. Export dial plan and backup PBX configs.
Week 1: Prep — provision SIP trunks to a non-production DID range, install or virtualize an SBC, set up QoS on LAN/WAN, and create monitoring dashboards (MOS, jitter, loss).
Week 2: Test — place 50–100 test calls across codecs, local and long-distance, and run stress tests for peak concurrency. Pass criteria: MOS ≥ 4.0, packet loss < 1%, jitter < 20 ms on voice VLAN.
Week 3: Pilot — route a subset of live inbound numbers to SIP (low-risk DIDs) and monitor for 7 days. Keep PRI active for fallback.
Week 4: Cutover planning — schedule porting windows, notify stakeholders, finalize rollback steps. Port numbers in small batches and validate after each batch.

Pass/fail quick checks — MOS ≥ 4.0 for three business-hour test calls, jitter ≤ 20 ms at the phone port, consistent carrier call completion for 10 sample calls.

Application to Canadian sites and personas

Operations manager, multi-site retail (Edmonton, Calgary, Red Deer): consolidate PRIs into a regional SIP pool, size bandwidth per 10 active calls (~500 kbps per call with overhead for G.711 and signalling), and keep a single PRI or LTE failover at critical POS sites. Assumes existing managed WAN and QoS policies in place.

IT director, small clinic in BC: prioritize location accuracy and PHI protection. Confirm how recordings and patient data transit carriers and follow BC PIPA and Alberta HIA where relevant. See provincial guidance for obligations for health data handling. PIPA details (OIPC BC). Alberta Health Information Act (HIA).

Contact centre manager: model concurrency pools and use session admission controls at SBCs to avoid over-commit. SIP is usually cheaper at scale, but you must instrument and alert on call queue metrics immediately after cutover.

Objections and pitfalls

“Our internet will never be good enough.” Possible response: add a redundant ISP or an LTE failover and use a hybrid design where the PRI remains as a local survivability circuit until you validate consistent call quality. Observability first; changes second.

“We can’t store recordings offsite for compliance.” Possible response: choose a carrier or platform that keeps recordings in your chosen Canadian region and restrict access by role. Treat retention as a policy design item before migration.

“Number porting will be messy.” Possible response: port in batches, keep parallel routing, and verify caller ID and CNAM after each port. Document the rollback plan and test it.

How our company solves this

Outcome: We reduce your telecom OPEX and restore predictable voice quality across sites. How we do it: We map sites and usage, run a short pilot with MOS and packet metrics, and present a 36-month TCO with all fees shown. CTA: If you want a neutral matrix filled with your Alberta or BC sites and numbers, tell us how many locations and we will build one.

Checklist: migration readiness (copyable)

Inventory numbers, PRI channels, analog devices, and DIDs.
Verify current internet performance during peak hours (latency, jitter, loss).
Plan SBC (high-availability if needed) and firewall rules.
Book porting windows and test calls for each batch.
Validate NG9-1-1 settings and keep an alternative phone during cutover.

FAQ

Do we have to replace every handset?

Often no. Gateways and SIP adapters can bridge legacy phones, though replacing very old handsets is usually cheaper over 24–36 months due to support and security updates.

How long does number porting take in Canada?

Simple ports often complete in a few business days; complex multi-carrier or geographic splits can take longer. Port in small batches and keep a rollback plan.

Can calls continue during an internet outage?