What Is the Difference Between SIP Trunking and Hosted PBX?
SIP trunking is a service that connects an existing on-premise PBX phone system to the public telephone network over the internet, replacing traditional phone lines while keeping your current hardware. Hosted PBX is a complete cloud-based phone system where the provider owns, manages, and maintains all the infrastructure, and your business accesses it through IP phones or softphone apps with no on-site equipment required. The right choice depends on whether you already own a PBX, how much IT capacity you have, and how quickly you need to scale.
SIP trunking keeps your existing PBX. It replaces copper phone lines with internet-based connections, lowering per-line costs while preserving your current hardware and configuration.
Hosted PBX replaces everything. The provider runs the entire phone system in the cloud. You plug in phones, download apps, and start calling with no equipment to maintain.
Cost structures are fundamentally different. SIP trunking charges per channel (concurrent call path), typically $15 to $30 per channel per month plus upfront hardware costs. Hosted PBX charges per user, typically $15 to $30 per user per month with no upfront hardware investment.
How SIP Trunking Works
SIP trunking uses the Session Initiation Protocol (SIP) to establish, manage, and terminate voice calls over your internet connection. A SIP trunk is a virtual phone line that connects your on-premise PBX to the SIP trunking provider, which routes your calls to the public switched telephone network (PSTN). Instead of physical copper lines running into your building, your PBX sends and receives calls through your existing internet connection.
The key requirement is that your business must already have an IP-enabled PBX or be willing to purchase one. The PBX handles all internal call routing, extensions, voicemail, auto-attendant features, and call management. The SIP trunk handles only the connection between your PBX and the outside world. You maintain full control over your phone system configuration, but you also carry full responsibility for maintaining, updating, and troubleshooting the on-premise equipment.
SIP trunking pricing is based on concurrent call channels rather than user count. If your business has 30 employees but only 10 people are on the phone at the same time during peak hours, you need 10 channels rather than 30 user licenses. This model favors businesses with high employee counts but moderate simultaneous call volume. Per-channel costs typically run $15 to $30 per month, but the upfront cost of the PBX hardware itself can range from $3,000 to $10,000 or more depending on the system and the number of extensions.
How Hosted PBX Works
Hosted PBX moves the entire phone system to the cloud. The provider owns the servers, manages the software, handles updates and security, and delivers the service to your business over the internet. Your employees connect using IP desk phones, mobile apps, or desktop softphones. There is no on-site PBX hardware to purchase, install, configure, or maintain.
The setup process is significantly simpler than SIP trunking. At Phone Service Now, we typically get a business fully operational on a hosted PBX system within one business day. You select your phone numbers, configure your extensions and call routing through a web-based admin portal, and your team starts making calls. Features like auto-attendant, voicemail-to-email, call recording, ring groups, and call forwarding are included in the service and managed through the same portal.
Hosted PBX pricing is per user per month. At Phone Service Now, plans range from $18.99 to $27.99 per user depending on the feature tier. There is no capital expenditure on PBX hardware, no maintenance contracts, and no need for on-site IT staff to manage the system. The provider handles all infrastructure, which means updates, security patches, and uptime are the provider’s responsibility. For businesses looking at the most affordable VoIP options, hosted PBX eliminates the largest cost barrier: the upfront hardware investment.
SIP Trunking vs. Hosted PBX Comparison
The differences between SIP trunking and hosted PBX fall into nine categories that matter most for business decision-making. This comparison covers the factors that determine total cost, operational complexity, and long-term fit.
| Factor | SIP Trunking | Hosted PBX |
|---|---|---|
| Infrastructure | Requires on-premise PBX hardware | No on-site equipment; everything is cloud-based |
| Upfront cost | $3,000 to $10,000+ for PBX hardware | $0 to $200 for IP phones or softphone apps |
| Monthly cost | $15 to $30 per channel | $15 to $30 per user (PSN: $18.99 to $27.99) |
| IT requirement | Needs in-house IT or managed services | Provider manages all infrastructure |
| Setup time | Days to weeks (hardware + configuration) | Typically 1 business day |
| Scalability | Add channels; may require hardware upgrades | Add users instantly through web portal |
| Control | Full control over PBX configuration | Provider controls system; you configure via portal |
| Remote work support | Requires VPN or additional configuration | Built-in; softphones and mobile apps included |
| Best for | Businesses with existing PBX and IT staff | Small to mid-size businesses without on-site IT |
The most common scenario we see at Phone Service Now is a business that considered SIP trunking because they assumed it would be cheaper, then chose hosted PBX once they factored in the PBX hardware cost, the IT overhead, and the time to get operational. For businesses starting from scratch with no existing phone infrastructure, hosted PBX is almost always the faster and more cost-effective path.
Not sure whether SIP trunking or hosted PBX is the right fit for your business? Our team can walk you through both options based on your current setup, team size, and budget.
When Does SIP Trunking Make More Sense?
SIP trunking is the better choice when a business has already invested in on-premise PBX hardware that still has years of useful life, has in-house IT staff or a managed IT provider capable of maintaining the PBX, needs granular control over call routing and system configuration beyond what a hosted PBX portal offers, or handles very high concurrent call volumes where the per-channel pricing model produces lower costs than per-user pricing.
The typical SIP trunking candidate is a mid-size to large business with 50 or more employees, an existing IP PBX, and an IT team that already manages the phone system. For these businesses, SIP trunking reduces monthly telecom costs by replacing expensive PRI lines with internet-based connections, often cutting per-line costs by 25 to 65 percent without requiring them to replace equipment that is still working. Businesses with specific compliance requirements around call recording, data sovereignty, or system customization also lean toward SIP trunking because they maintain physical control over the PBX.
When Does Hosted PBX Make More Sense?
Hosted PBX is the better choice for businesses that do not own a PBX and do not want to buy one, have no in-house IT staff or limited technical resources, need to support remote or hybrid workers with softphones and mobile apps, want predictable monthly costs with no capital expenditure, or are growing and need the ability to add lines instantly without hardware upgrades.
One question we hear constantly from small business owners choosing a business phone system is whether they are giving up too much control by going with hosted PBX. The answer for most small businesses is no. The web-based admin portal on a good hosted PBX platform gives you control over call routing, auto-attendant menus, ring groups, business hours, voicemail, and user management. What you give up is the ability to modify the underlying telephony software and hardware, which most small businesses never need or want to do.
The businesses that benefit most from hosted PBX are medical practices, law firms, real estate teams, home service companies, and staffing firms with 5 to 100 employees and no dedicated IT department. These are the exact business types we work with most at Phone Service Now, and the hosted PBX model is what allows them to have an enterprise-grade phone system at a fraction of the cost of building one in-house.
Common Mistakes When Choosing
Providers often come to us after making a phone system decision they regret. These are the mistakes that cost businesses the most time and money.
Choosing SIP trunking without an existing PBX. If you do not already own an IP-enabled PBX, the hardware cost erases the per-channel savings. A new PBX plus installation, configuration, and ongoing maintenance typically costs $5,000 to $15,000 before you make your first call. Hosted PBX eliminates that entire cost category.
Assuming per-channel pricing is always cheaper. SIP trunking charges per concurrent call path. If your team makes a lot of simultaneous calls, you need more channels, and the cost advantage over per-user hosted PBX pricing narrows or disappears. Model both pricing structures against your actual call patterns before deciding.
Underestimating the IT burden of SIP trunking. Your PBX is a server. It needs firmware updates, security patches, and someone who knows how to troubleshoot it when calls drop or quality degrades. If you do not have that person on staff, you will either hire one or pay a managed IT provider, both of which add to the real cost of SIP trunking.
Not testing remote work support. SIP trunking was designed for office-based systems. Making it work for remote employees requires VPN configuration, SIP-compatible softphones, and firewall adjustments that are not straightforward. Hosted PBX includes remote access by default through softphone apps and mobile integration.
Frequently Asked Questions
What is SIP trunking?
SIP trunking is a service that connects your on-premise PBX phone system to the public telephone network over the internet using the Session Initiation Protocol. It replaces traditional copper phone lines with virtual connections, reducing per-line costs while allowing you to keep your existing PBX hardware and configuration.
What is hosted PBX?
Hosted PBX is a cloud-based phone system where the provider owns and manages all the telephony infrastructure. Your business accesses the system through IP desk phones, softphone apps, or mobile devices. There is no on-premise equipment to purchase or maintain, and features like auto-attendant, voicemail, and call routing are included.
Which is cheaper, SIP trunking or hosted PBX?
It depends on your starting point. If you already own a PBX, SIP trunking has lower monthly costs because you pay per channel rather than per user. If you do not own a PBX, hosted PBX is cheaper overall because it eliminates the $3,000 to $10,000 or more in hardware costs. Factor in IT maintenance when comparing total cost.
Can I use SIP trunking without a PBX?
No. SIP trunking requires a PBX to manage your internal phone system. The SIP trunk only provides the connection between your PBX and the outside telephone network. If you do not have a PBX, you need a hosted PBX or another cloud-based phone solution that includes the full phone system.
Is hosted PBX reliable enough for a business?
Yes. Reputable hosted PBX providers deliver 99.9 percent or higher uptime through redundant data centers and automatic failover. Call quality depends primarily on your internet connection. A business-grade internet connection with adequate bandwidth and quality of service settings provides call quality comparable to traditional phone lines.
Can I switch from SIP trunking to hosted PBX later?
Yes. Switching from SIP trunking to hosted PBX involves porting your phone numbers to the new provider, configuring your extensions and call routing in the hosted PBX portal, and deploying IP phones or softphone apps. The transition typically takes one to five business days. Your existing PBX hardware can be decommissioned after the switch.
Does hosted PBX support multiple office locations?
Yes. One of the primary advantages of hosted PBX over SIP trunking is multi-location support. All locations share the same phone system, dial plan, and extension directory through the cloud. Adding a new location requires only an internet connection and IP phones or softphone apps at the new site.
Next Steps
If you already own an IP PBX with useful life remaining and have IT staff to manage it, SIP trunking may reduce your monthly telecom costs without replacing your current system.
If you do not own a PBX, have limited IT resources, or support remote workers, hosted PBX gives you a complete business phone system with no hardware investment. Review our guide to choosing the right business phone system for a broader comparison of the options available in 2026.
Ready to move your business phone system to the cloud? Phone Service Now provides hosted PBX with plans starting at $18.99 per user, one-day setup, and no hardware to buy. Talk to our team about getting your business connected.