The difference between fixed and non-fixed VoIP numbers isn’t particularly complex, though it may not be readily apparent to someone who doesn’t fully understand what VoIP is to begin with. In short, fixed VoIP numbers are associated with an account holder’s physical address while non-fixed VoIP number aren’t fixed to any specific address.

While that sentence summarizes the core difference between fixed and non-fixed lines, there are many finer points to understand about each of these. Pros and cons for fixed versus non-fixed VoIP numbers range from one having more security and reputability to the other being easier to set up and offering greater flexibility.

What is a Fixed VoIP Number?

Before drilling down into the details of non-fixed VoIP numbers, it’s worth knowing what a fixed number is. Again, fixed VoIP lines are associated with a physical address, such as someone’s home or a company’s office. This is similar to traditional phone services, which require an address for service to be provided, as do many mobile accounts.

Because it’s linked to the street address of an account owner, fixed VoIP numbers tend to be less frequently used for spam and fraudulent activity. That being the case, fixed VoIP numbers are viewed with an additional degree of authenticity and reputability. In turn, VoIP providers more likely to support 911 calls on fixed VoIP lines versus non-fixed, which have no address on file where first responders can be dispatched.

Along with being linked to an account’s address, fixed numbers are usually connected back to a VoIP provider’s telephony station such as through a SIP trunk instead of operating entirely on the Internet. Fixed numbers also tend to be paid accounts and are not issued by free services with a quick signup, as you might experience when creating a new account with Skype for instance.

What is a Non-Fixed VoIP Number?

Whereas fixed numbers are linked to a physical address, non-fixed VoIP numbers don’t require a fixed address and instead can be associated with any geographical location. VoIP accounts with non-fixed numbers can be created with an address where the account creator doesn’t live or have an office.

These types of numbers are also known as “virtual phone numbers” and are commonly issued by free services such as Skype and Google Voice. They rarely require anything more than an email registration and maybe some payment information if relevant, though access to these platforms tends to be free.

Because these services offer great flexibility for global communication, such as in the case of facilitating collaboration between remote teams, the non-fixed VoIP numbers issued by these types of Web services certainly have their place in business. For example, if your company has employees in different countries, they could be contacted without incurring charges for long distance or international calling.

Non-fixed VoIP numbers are ideal for enabling some of those more business-oriented features. For instance, someone with a fixed VoIP line might request a virtual phone numbers through their VoIP provider who will often charge a fee each virtual number, and this number could be issued with a specific area code so that when someone calls the virtual line, the call is registered as being local but is automatically forwarded to a non-local number.

While they have business purposes, non-fixed VoIP lines are more frequently used for personal use and generally lack the breadth of professional features that people would typically associate with VoIP telephony. VoIP services with Nextiva, Vonage or other providers come with dozens of advanced cloud calling features such as call flip, which lets you move calls from one device to another at the press of a button, while you won’t find nearly as many capabilities on non-fixed lines, and certainly not as many business-oriented capabilities.

Because they are so affordable, easy to access, and often difficult to trace, non-fixed VoIP numbers are more disposable than a fixed VoIP number and are more commonly used for criminal activity – we’ll elaborate on this shortly.

Fixed vs. Non-Fixed VoIP – Pros & Cons

To summarize, there are advantages and disadvantages to fixed and non-fixed VoIP numbers depending on the application and circumstances surrounding their use.

Fixed VoIP Pros:

  • More authentic, less used for crime and thus has a better appearance and reputation.
  • Fixed VoIP lines generally come with more advanced calling and call routing features.
  • Dependable emergency 911 calling as an address is associated with the account.

Fixed VoIP Cons:

  • Requires an address where service is piped and thus is more involved to obtain.
  • More expensive. The service is more involved to turn on and features aren’t free.
  • Pricier international calls and stricter pricing in general based on your location.

Non-fixed VoIP Pros:

  • Not inherently bound to any geographical location or street address.
  • Easy to obtain through online services that usually only ask for an email registration.
  • These services are generally free or inexpensive compared to fixed VoIP lines.
  • Great if you or your company handles a lot of international calls.

Non-fixed VoIP Cons:

  • More commonly used by criminals and is thus less authentic and trustworthy.
  • Less professional appearance, especially for a primary business line.
  • May not be able to make emergency 911 calls because no location is assigned to the number.

Why Spammers Love Non-Fixed VoIP

Again, non-fixed VoIP numbers don’t have to be linked to an account holder’s physical address and these types of lines can be easily opened by someone who is outside a specific country with little more than an email confirmation and rarely even requiring payment information.

New non-fixed VoIP numbers can be generated easily and caller ID information can be spoofed, allowing criminals such as spammers who are overseas to make anonymous calls or to impersonate other people when placing orders with stolen credit cards. When combined with the ease of access, affordability and the ability to perform bulk dialing through IP telephony systems with a basic script, it’s easy to understand the appeal of non-fixed VoIP for spammers.

This type of activity has given rise to the development of new systems designed to counteract instance when non-fixed numbers are used for fraud. APIs such as Whitepages Pro Phone Solutions exist that allow users to identify what type of number someone is calling from based on various data points that are meshed into a reputation score whereby numbers over a certain threshold have a high likelihood of being spam or otherwise unscrupulous.

Likewise, it is now possible to identify non-fixed calls based on the number being linked to a non-fixed VoIP service when the caller ID information is retrieved.

The Bottom Line: Non-Fixed VoIP

Fixed and non-fixed VoIP have pros and cons that make them more or less ideal for a given scenario. For circumstances such as a company requiring a lot of advanced calling features and support for 911 emergency calls, a fixed VoIP line makes the most sense.

Conversely, non-fixed VoIP numbers can be useful when simply looking to create a quick line that can be used for personal calls, call forwarding capabilities or for making international calls that might cost more to place through a fixed VoIP line.