SIP Trunking
SIP Trunking for Business —
Replace PRI Lines, Cut Voice Costs 40–70%
Replace PRIs with SIP trunking — lower cost, more flexibility.
No cost · No obligation · Results in 24 hours
What Is It
What is SIP trunking and why are businesses replacing PRI?
SIP (Session Initiation Protocol) trunking replaces the physical telephone lines connecting your PBX to the PSTN (public switched telephone network) with internet-based voice channels. Instead of a PRI circuit (23 channels, fixed cost) or individual analog lines, your calls travel over your existing internet connection to a SIP provider — at a fraction of the cost.
A typical PRI circuit provides exactly 23 simultaneous call channels at a fixed monthly cost. SIP trunking for the same capacity costs significantly less, with the ability to instantly add or remove channels as call volume changes. You keep your existing phone numbers, your existing PBX or IP-PBX, and your existing handsets. The only thing that changes is the connection between your PBX and the outside world.
Fibi evaluates your current voice setup, call volume, and growth plans, then compares SIP providers on quality, pricing, geographic number availability, failover options, and compatibility with your specific PBX platform. We manage the porting of your existing numbers to the new provider and coordinate the cutover to minimize disruption.
Why It Matters
Key benefits for your business
40–70% Cost Reduction
Replace an expensive PRI circuit with SIP channels at a fraction of the cost. The savings are immediate. Most businesses recover the cost of any required SIP gateway hardware within 2–3 months of switching.
Instant Capacity Scaling
Add a new call channel in minutes — no waiting weeks for the phone company to provision a new circuit. Scale up for busy season and scale down when volumes drop. You only pay for what you use.
Geographic Number Portability
Add local numbers in any US area code (or international DID numbers) without physical infrastructure in that city. A Chicago business can answer calls to a Dallas number as if they were local.
Built-In Redundancy
Quality SIP providers offer geographic redundancy — if one of their data centers fails, calls automatically route through another. Combined with a secondary SIP trunk from a different provider, you get true voice continuity.
PBX Compatibility
SIP trunking works with virtually all modern IP-PBX systems (Cisco, Avaya, Mitel, 3CX, FreePBX) and connects to legacy TDM PBX systems via SIP gateways. You don't need to replace your phone system to benefit.
Detailed Call Analytics
SIP providers deliver call detail records (CDRs) with more granularity than legacy carriers — by DID, by extension, by time of day. Use the data to optimize staffing, identify dropped calls, and measure response times.
The Fibi Advantage
PRI/T1 vs. going direct to a SIP provider vs. Fibi
Who Needs This
Built for businesses like yours
Replacing Legacy PRI Lines
The most common use case: your PRI contract is up for renewal and you want to stop overpaying for 23 fixed channels. SIP delivers the same capacity at significantly lower cost, with number portability included.
Multi-Location Businesses
Consolidate voice connectivity across all your locations onto a centralized SIP platform. Eliminate per-location PRI circuits and manage all phone numbers, call routing, and capacity from one portal.
Contact Center & Call Centers
SIP's elastic channel capacity is ideal for contact centers — scale from 50 to 500 concurrent calls instantly during campaigns. Per-minute and per-channel SIP pricing beats traditional voice circuit costs significantly at volume.
Disaster Recovery Voice
Configure your SIP trunks to automatically reroute to a backup location, a mobile number, or a cloud IVR if your primary office goes offline. Voice continuity that would have required expensive PSTN arrangements is now built into SIP.
Cloud PBX Migration Bridge
SIP trunking can serve as a transitional solution while you migrate from a legacy PBX to a cloud UCaaS platform — or as a permanent architecture if you want to keep your on-premises PBX.
International Calling Cost Reduction
International per-minute rates on SIP trunks are 50–90% lower than traditional carrier international rates. Businesses with significant international call volume often recover the entire SIP setup cost within a single month.
FAQ
Common questions
Free Advisory
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Tell us what you need. We'll go to market across our full carrier network and return a side-by-side comparison within 24 hours — at zero cost to you.