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Fixed vs Non Fixed VoIP

by Margaret Joy

What's the difference between fixed and non fixed VoIP, and which is better? We explain why the options exist and what they mean today.

We’ve brought up fixed vs non fixed VoIP before, as part of our “What is VoIP?” deep dive. But we felt it was due for a dedicated blog. Fixed vs non fixed VoIP is another “this or that” question that crops up when setting up your business VoIP system, much like hosted (cloud) VoIP vs an on-premise system. It comes with its own list of pros and cons and eventually comes down to what works best for you. Fortunately, this particular question is much more simple than the other. And, as we get into at the end, it’s not really much of a question any more at all. 

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 hosted VoIP. Additionally, the number can only be used at that location and requires an area code that matches the address. You can see the term choice—the number is “fixed” to that location. It also has a bit more of a connection to the PSTN than regular VoIP numbers because that’s how the address for the number is established. 

Non Fixed VoIP Meaning 

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 might enter a location in admin settings for E911 purposes, but there is no set physical location for the number. 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 between 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. But up 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 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 E911 now, not to mention the ongoing NG911 implementation, and it’s pretty easy to just add your current location for any VoIP phone number. Plus, smartphones came about after VoIP so not only will you likely have a cell phone on you, you might even use that cell phone 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.”


Now we’re not saying that if you want a fixed VoIP number, you shouldn’t go for it. Since the pros of a fixed VoIP system have largely become mitigated by advancements in technology, choosing between fixed and non fixed VoIP is truly about finding what works best for you and your company. Be aware of these two options and factor them into your decision-making process as you’re searching for your new VoIP provider.

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