Receive unlimited incoming VoIP calls with FlyNumber’s virtual phone numbers and SIP2SIP

5.00 avg. rating (94% score) - 1 vote

Recently I was introduced to FlyNumber, an easy-to-use cloud VoIP provider which offers PBX services as well as virtual phone numbers for many countries around the world. This article will show you how to use FlyNumber to purchase a phone number for, let’s say, US or Canada, and receive incoming calls to this number on your favorite softphone client such as Zoiper with just a few configuration steps.

First open FlyNumber’s virtual phone numbers page and select a country where you want your virtual phone number to be located in. In my test, I chose Canada, which has a very affordable rate of just 2.95 USD monthly. After making payment via Paypal, you should be able to access the options for the virtual number:

Screenshot 2023-04-30 234653

Under “Forwarding Details” you can specify what will happen if somebody calls this number. You can choose to forward the call to a normal PSTN or mobile number (which will cost extra depending on the destination), to FlyNumber’s own phone system (which requires purchasing FlyNumber’s own PBX services), to a supported provider (Callcentric, Callwithus, etc.), or simply to another SIP service. Using the instructions here I decided to register an account with SIP2SIP in order to forward incoming calls to this account. Unlike other services, the registration interface for SIP2SIP is very simple – my account was immediately created after clicking the Sign Up button:

Screenshot 2023-04-30 235512

Next, in Zoiper, add an account pointing to the just created SIP2SIP account. After a few seconds, Zoiper should report that the account has been successfully registered:

Screenshot 2023-04-30 235608

Next, inside the configuration panel for the virtual phone number, under section Forwarding Details, select VoIP, enter as host, your account’s username as details, and click Update:

Screenshot 2023-04-30 235946

Now try to make a call and Zoiper should ring immediately. If Zoiper doesn’t ring, check to make sure that the configured username and password matches the credentials you set for your SIP2SIP account, and that the same username has been entered in the “details” section of the virtual phone number configuration.


Answer the call and you should be able to establish two-way communication. During my tests, audio was very clear and quality was great, using G711U/PCMU codec:


This is the Wireshark packet capture of the incoming SIP INVITE request:

Screenshot 2023-05-01 000556

Interestingly, as can be seen from the packet capture, the incoming call passed through two different IPs, and, both of which are located in Europe, even though the DID I used for my test is located in Canada. The second IP,, belongs to DIDWW, an Ireland VoIP provider. Despite the multiple hops, incoming calls are connected almost immediately and audio quality is just great, with no lags observed. In my opinion, using FlyNumber with SIP2SIP is a cost-efficient method to receive unlimited incoming calls, no matter where you are in the world.

You can click here to learn more about FlyNumber’s virtual phone number services and purchase your own number to try it out. Feel free to leave a comment below to share your experience.


5.00 avg. rating (94% score) - 1 vote


A tough developer who likes to work on just about anything, from software development to electronics, and share his knowledge with the rest of the world.

One thought on “Receive unlimited incoming VoIP calls with FlyNumber’s virtual phone numbers and SIP2SIP

  • May 1, 2023 at 4:50 am

    Really great article – we’ll be sure to send users here when they need help setting up Zoiper and sip2sip.

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