VoIP Buying Guide.

/ 01How VoIP actually works

Understanding the basics helps with vendor evaluation and troubleshooting.

VoIP (Voice over Internet Protocol) digitizes audio, packages it into IP packets, and sends those packets over the internet to the recipient — who reassembles them and plays back the audio. The conversion happens many times per second. Latency over 150ms or packet loss above 1% produces audible quality problems.

The major components:

• Endpoint — the device you talk on. A SIP-capable desk phone (Polycom, Yealink, Grandstream, Cisco), a softphone app on your computer or mobile, or an ATA adapter for legacy analog phones
• PBX (Private Branch Exchange) — the brain that routes calls within your organization and between your endpoints and the outside world. Either hosted in the cloud by your provider, or running on-prem on a server in your closet
• SIP trunk — the digital connection from your PBX to the public telephone network. Replaces the old "T1" or "PRI" lines. Sized by concurrent call capacity
• Phone number provider (CLEC/RespOrg) — the carrier that owns or routes your phone numbers
• Internet connectivity — the underlying transport for all of this

In a hosted PBX setup, your provider operates the PBX and SIP trunks; you just have endpoints. In a self-hosted setup, you operate the PBX yourself (often on an on-prem appliance or cloud VM) and buy SIP trunks separately.

/ 02The three deployment models

Hosted PBX (UCaaS — Unified Communications as a Service)

Provider runs everything in the cloud. You get a desktop app, mobile app, and optionally desk phones. Per-user monthly pricing usually includes unlimited US/Canada calling.

Vendors: RingCentral, Nextiva, GoTo Connect, 8x8, Zoom Phone, Microsoft Teams Phone, Vonage, Dialpad, Sangoma Switchvox Cloud.

Pros: Predictable monthly cost, no on-prem hardware to maintain, scales easily, full mobile/remote support, included features (call recording, conferencing, integrations).

Cons: Ongoing cost is higher in the long run, less customization, dependent on internet (failover required), vendor lock-in if you want to switch.

Best for: Most SMBs under 200 users, organizations with distributed/remote workers, anyone who doesn't have IT capacity to run their own PBX.

Cloud-managed on-prem (Sangoma PBXact, 3CX self-hosted, FreePBX with commercial support)

PBX runs on an appliance or server in your office (or in your cloud VM). Vendor provides licensing, updates, and support. You buy SIP trunks separately from a trunk provider.

Pros: Lower long-term cost, more customization, less dependent on a single vendor, you own the data, dial-tone survives internet outages if SIP trunks are still up (some setups).

Cons: Hardware to maintain, more IT involvement, longer initial deployment, SIP trunk relationship to manage separately.

Best for: Organizations with strong internal IT or MSP support, businesses with custom integration needs, larger SMBs where the per-user math favors ownership.

Fully self-hosted (FreePBX, Asterisk, FusionPBX, vanilla 3CX)

You operate everything. Open-source PBX, your own hardware, your own SIP trunks. Maximum control, minimum cost on licensing, maximum operational complexity.

Pros: Lowest cost at scale, completely customizable, no vendor lock-in.

Cons: Requires real telephony expertise, no commercial support unless you buy it, you're responsible for security, updates, integration, and troubleshooting.

Best for: Organizations with telephony engineers on staff. Almost never the right choice for a typical SMB.

/ 03Features that actually matter

Most VoIP marketing lists 50+ features. Here's what actually matters for typical business use:

Core (every provider has these)

• Auto-attendant / IVR ("press 1 for sales...")
• Hunt groups and ring groups
• Voicemail with email delivery
• Call transfer (warm and cold)
• Call recording
• Conference calling
• Mobile app for iOS and Android
• Desktop softphone

Worth verifying explicitly

• Unlimited US/Canada calling — most include this; verify it's actually unlimited (some have "fair use" caps around 3,000 minutes/month/user)
• Number porting — included, with reasonable timeline
• E911 compliance with dispatchable location (Kari's Law / RAY BAUM's Act)
• SMS / text messaging from business number — increasingly important; not all providers offer it well
• CRM integrations — Salesforce, HubSpot, Microsoft Teams, etc.
• Call queues for support/sales teams with longer hold times
• Hot desking / mobile DID for shared workstations
• Reporting and analytics — call volume, response times, missed calls

Premium features (verify if needed)

• Advanced contact center features (skills-based routing, supervisor barge/coach)
• Real-time call analytics
• AI transcription and sentiment
• Video meetings integrated with phone
• Microsoft Teams integration as the calling provider
• International calling rates (verify these — biggest pricing trap)

Don't pay extra for

• "Advanced features" that should be standard — voicemail-to-email, basic call recording
• "HD voice" — every modern codec is HD-capable
• "99.99% uptime SLA" — easy to claim, rarely meaningful in practice (read the credits/remedies fine print)

/ 04Hidden costs and gotchas

Regulatory recovery fees

Federal Universal Service Fund (USF), state telecommunication taxes, local franchise fees. These add 8-20% to your bill on top of the advertised price. They're real and legally required, but watch for "regulatory recovery fees" line items that exceed the actual government-mandated charges — some providers tack on extra margin disguised as taxes.

911 / E911 fees

Typically $1-$3 per line per month. Sometimes per user, sometimes per DID (Direct Inward Dial number). Often "free" for the first X lines, then per-line. Read the fine print.

Desk phone leasing

"Free phones with your service" usually means you're financing them at well above retail in your monthly fees. A Yealink T46U costs $190 retail; "free" in a lease might cost you $8/month for 5 years = $480. Buy your phones outright unless you have a strong reason not to. They keep their value, you own them, you can switch providers without phone replacements.

"Free" minutes that aren't

"Unlimited" plans often have fair-use caps. International rates vary wildly. Toll-free inbound is usually per-minute, not unlimited. SMS messages may be metered. Calling Hawaii, Alaska, or Puerto Rico is sometimes excluded from "US unlimited." Conference call participants beyond X may be charged.

Contract lock-in

1-3 year contracts are common. Early termination fees can be brutal ($200+ per user per remaining month). Auto-renewal clauses with 60-90 day cancellation windows. Verify exit terms before signing.

SIP trunk overage

If you bought 10 concurrent SIP trunks and call 11 simultaneously, the 11th caller hears a busy signal. Or you pay overage rates. Plan capacity carefully.

Number porting fees

Most providers absorb the cost of porting numbers in (they want your business). When you leave, they may charge $25-$100 per number to port out. Verify exit costs.

/ 05How to evaluate a vendor

Questions worth asking every VoIP vendor before signing:

1. What is my actual monthly total — including all taxes, regulatory fees, 911 fees — for X users? Get it in writing.
2. What's the contract length and the exit clause? Look for month-to-month options even if more expensive.
3. What's your uptime SLA, and what do I get if you miss it? Vague SLAs without remedies aren't SLAs.
4. How long has your platform been operating, and what's your scheduled-maintenance pattern?
5. What happens to my phone numbers if I leave? They should port out without charge or with minimal charge.
6. Do you support Kari's Law and RAY BAUM's Act E911 requirements? Yes is required by federal law.
7. What's included for unlimited calling — US, Canada, Mexico, international? Any caps?
8. What features are included vs add-on? Common add-ons that surprise people: call recording, SMS, integrations with major CRMs.
9. How does my service work during an internet outage? Look for: call forwarding to mobile, mobile app continues to work over cellular, optional cellular failover.
10. What support do you provide — 24/7? Phone, email, chat? US-based?
11. Can I keep my existing desk phones, or do I need new ones? Most modern SIP phones are interoperable, but verify with your specific models.
12. Can I see a current customer's actual monthly invoice (sanitized)? Real billing samples reveal what marketing pages hide.

/ 06How a transition works

A typical SMB VoIP migration takes 3-6 weeks from contract signing to old service cancellation.

Weeks 1-2: Setup

• Account provisioned with new provider
• Internet bandwidth verified (QoS configured on firewall)
• Desk phones ordered and shipped
• User accounts and extensions configured
• Auto-attendant, IVR, ring groups, voicemail boxes built
• Number porting initiated (this is the long pole)
• Existing service kept active

Weeks 2-4: Testing

• Desk phones installed
• Mobile and desktop apps deployed to users
• Test extensions live; users practice with internal calls
• Verify call quality, voicemail, transfer behavior
• Train users on new features
• Test failover scenarios

Cutover day (typically a Friday afternoon)

• Number port completes; calls now route to new system
• Old system kept available for 7-14 days as safety net (call forwarding rules)
• Verify inbound and outbound calls working
• Verify 911 routing with dispatchable location
• Brief team again on any post-cutover changes

Post-cutover (week +1 to +4)

• Cancel old service after porting confirmed and 7-day shakedown
• Adjust ring groups, voicemail, and routing based on real-world experience
• Train any users who missed initial sessions
• Document the final configuration

Most VoIP transitions go smoothly when planned. The two biggest failure modes are: porting delays (rare but happen — keep old service active until porting confirmed) and inadequate internet QoS (fixable with proper firewall configuration).