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Fixed vs Non-Fixed VoIP Meaning: Phone Numbers and VoIP

by Margaret Joy

What's the difference between fixed and non-fixed VoIP phone numbers? Read our deep dive blog post exploring the non-fixed VoIP meaning and why these exist.

We’ve brought up fixed vs. non-fixed VoIP before, as part of our “What is VoIP?” deep dive. But we felt it deserved a dedicated blog.

Fixed vs. non-fixed VoIP is another “this or that” question that emerges when setting up your business VoIP system, much like hosted (cloud) VoIP vs. an on-premise system. It has its own list of pros and cons and eventually comes down to what works best for you. Fortunately, this particular question is much simpler to answer than the other. And, as we explain later, it’s not really much of a question anymore.

What Does Fixed VoIP Mean?

A fixed VoIP phone number is a VoIP number, but it functions a bit more like a landline in that it is tied to a specific address. That means it takes a bit more work to provision than a typical VoIP number, much like setting up a landline phone system instead of a cloud-based system (hosted VoIP). Additionally, the number can only be used at that location and requires an area code that matches the address. You can see it in the name—the number is “fixed” to that location. It also has a bit more of a connection to the Public Switched Telephone Network (PSTN) than regular VoIP numbers because that’s how the address for the number is established.

What Does Non-Fixed VoIP Mean?

This is your typical VoIP setup. It’s a phone number that can be used from anywhere so long as you can sign in with your SIP address. You enter a physical location in admin settings for E911 purposes, but unlike a non-fixed VoIP number, it isn’t anchored to that location. We talk a lot about how VoIP is great for mobile and remote teams—and this is one of the biggest reasons why. Another is that a non-fixed VoIP phone can have any area code you choose, no matter where you might have your office.

So you might be wondering, if one of the best benefits of using cloud VoIP is its mobility, why would anyone use a fixed VoIP number? Well for starters, VoIP is still a much better option than a landline system when it comes to setup, cost, and maintenance, so if you’re going to have a set location you might as well have it all under the same provider. Until recently, there was a pretty solid set of pros and cons for each. However, the changes in telecommunications standards and the ongoing migration away from the traditional PSTN have mostly rendered the pros of a fixed VoIP phone moot.

Fixed VoIP and the PSTN

A good VoIP provider, like OnSIP, will make sure your VoIP calls spend as little time on the PSTN as possible. The Internet is faster and has better quality, after all. But since fixed VoIP numbers are tied to the PSTN because of their fixed location, they connect a bit more directly. Like we said above, they are VoIP numbers, but they function much more like landlines. And that connection is the basis for most items in the “Pros” column when comparing the two.


We all know that an Internet connection is easier to hack than a landline, so in the past, fixed VoIP numbers were seen as a stronger security option. Luckily there are good VoIP providers who prioritize security, like OnSIP, to ensure end-to-end encryption on your calls and protect your system.


Having a fixed VoIP number means that when you call emergency services, the dispatcher sees your location pop up right away, just like calling from a landline. But we have Enhanced E911 now, not to mention the ongoing Next Generation 911 (NG911) implementation, and it’s pretty easy to just add your current location for any VoIP phone number. Plus, smartphones rose in popularity after VoIP so it’s likely you have one on you and might even use it as your work phone with a softphone app! That’s the second pro crossed off the list.

Official Communications

There are some things you can’t use a non-fixed VoIP number for—or at least there were in the past. Things like an emergency contact number, the number associated with your bank accounts, and so on. Because there’s no address directly tied to a non-fixed VoIP number, they weren’t seen as authentic enough for official communications. But between new FCC standards like STIR/SHAKEN that combat spoofing and other scams, and the ongoing PSTN sunset, VoIP numbers are much more easily authenticated now than in the past—plus landlines won’t exist for much longer.

And that rounds out the collection of “Why the advantages of a fixed VoIP system are now moot.”

Non-Fixed VoIP Meaning

We’re not saying that if you want a fixed VoIP number, you shouldn’t go for it. But the pros of a fixed VoIP system have largely become mitigated by advancements in technology. With the non-fixed VoIP meaning revealed, you are now ready to choose between fixed and non-fixed VoIP. It’s truly about finding what works best for you and your company as you search for your new VoIP provider.

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