Your current phone system is probably costing you more than it should and locking you into inflexible contracts. The choice between SIP trunks and traditional VoIP often comes down to your business size, infrastructure, and budget—and the wrong pick can waste thousands annually. Let's break down what each option actually does so you can make a decision that fits your operation.
What's the Real Difference?
SIP trunks and VoIP are often used interchangeably, but they're not the same thing. VoIP (Voice over Internet Protocol) is the umbrella technology that transmits voice through internet data packets instead of old copper phone lines. SIP (Session Initiation Protocol) is a specific protocol that manages how those calls are set up, routed, and ended.
Think of it this way: all SIP trunks are VoIP, but not all VoIP services use SIP. Most modern business phone systems use SIP trunks because they're the industry standard for reliability and scalability. Hosted VoIP services (sometimes called cloud-based phone systems) also transmit over the internet but handle infrastructure differently—the provider maintains everything in the cloud, while SIP trunks typically connect to your existing on-premise phone system like a legacy PBX.
When SIP Trunks Make Sense
SIP trunks work best if you've already invested in an on-premise PBX system or want direct control over your phone infrastructure. You're essentially replacing the old trunk lines that connected your office to the telephone company with internet-based connections.
Ideal scenarios for SIP trunks:
- Your business operates multiple office locations and needs seamless call routing between them
- You have an existing PBX investment you want to protect and extend
- You need custom call workflows or integration with legacy telephony equipment
- You want your phone system housed on-site for security or compliance reasons
Monthly costs typically run $15–$30 per trunk, plus setup fees ($200–$500). You'll need adequate bandwidth—at minimum 100 Kbps per call in each direction, but plan for 200 Kbps if you use video or share the connection with other data. A 20-person office might use 3–5 trunks and pay $200–$400 monthly, depending on your provider and call volume.
When Hosted VoIP Wins
Hosted VoIP (cloud-based phone systems) eliminates the need for on-premise hardware entirely. Everything runs through your internet connection and the provider's data center. This approach suits growing companies that want simplicity and flexibility without managing their own equipment.
Go with hosted VoIP if:
- You want to avoid capital investment in phone hardware
- Your team is remote, hybrid, or geographically scattered
- You need fast deployment—most systems are up and running in days
- You prefer predictable monthly costs with no hidden infrastructure expenses
- You want built-in features like voicemail-to-email, call recording, and mobile apps without extra charges
Hosted VoIP typically costs $25–$50 per user monthly, with most plans including unlimited local and long-distance calling. Small teams of 5–10 users can get started for $125–$250 monthly. Larger deployments (50+ users) often qualify for volume discounts, dropping to $20–$35 per user.
Key Comparison Points
Reliability and redundancy: SIP trunks depend entirely on your internet connection and on-premise equipment. If your internet fails, calls fail. Hosted VoIP has built-in redundancy—calls automatically reroute if one data center goes down, and mobile apps keep staff connected even if your office is offline.
Scalability: Adding users to hosted VoIP takes minutes and costs the same whether you hire 2 people or 20. SIP trunks require careful capacity planning and may mean buying additional trunks or upgrading your PBX. Scaling down is also easier with hosted solutions—no long-term contracts on per-user plans.
Integration: SIP trunks integrate naturally with existing PBX systems. Hosted VoIP integrates with CRM platforms, Slack, Microsoft Teams, and hundreds of business apps through native connectors or APIs.
Total cost: For a small business (under 15 people), hosted VoIP usually costs less and requires zero hardware investment. For large enterprises with complex call routing needs, SIP trunks can be more economical after the initial infrastructure investment.
Making Your Decision
Start by auditing your current system: How many calls per day? How many users? What's your internet reliability rated (uptime percentage)? Do you have on-premise phone equipment that's still functional and worth keeping? Answer these honestly, and the right choice becomes clear.
If you're unsure where to start, Mercoly helps you compare and find trusted Business Phone & VoIP Systems providers in one place, so you can match your needs to the best fit without endless research.
Frequently Asked Questions
Q: Can I switch from SIP trunks to hosted VoIP later, or vice versa? Yes, but it requires ripping out your current system, so plan for downtime (typically a few hours) and retraining staff. Starting with the right fit saves that hassle.
Q: Do SIP trunks or hosted VoIP work with my existing office phones? Hosted VoIP requires compatible phones (usually IP phones) or apps on computers and mobile devices. SIP trunks work with your current PBX as long as it supports SIP technology, which most modern systems do.
Q: What internet speed do I actually need for either option? Minimum 5 Mbps for 5 users, 10 Mbps for 10–20 users, and 25 Mbps for 50+ users—but always check your provider's specs, especially if you're also streaming video or using cloud software heavily.
Get quotes from at least three providers in your area to compare pricing, features, and contract terms before committing.