SIP, which stands for Session Initiation Protocol, is a signaling protocol to begin and end online communication, such as internet telephony, telepresence, games, and chat. You can use your SIP address to make free SIP-to-SIP phone calls with your computer, your smartphone, or your Wi-Fi-enabled tablet. This simple guide will explain how.

Step 1: Get a SIP address:

You can get a SIP address for free from most business VoIP providers. They will give you a free SIP address, even if you don’t sign up for their services. Your SIP address if you do will be “” You’ll create a login, pick a password as well.

Google provided SIP addresses in 2011 but stopped shortly thereafter. There are other web sites you can use to register a SIP address, or you can also get one from your VoIP provider.

Step 2: Get a SIP Client or App

A SIP client is a program that you install on your computer, smartphone, or tablet. It is a specialized softphone that can connect to other SIP addresses. There is no shortage of apps for your tablet or smartphone, and many of them are free. If you don’t know which one to use, I suggest you start with Linphone, a free SIP VoIP client. Linphone works on every major computing and mobile platform, and it’s open-source and free.

Go to the settings of your app. Depending on your device, the settings may be inside the app itself or in the settings of the device. Enter your username, domain, and password into the settings. Your SIP address is now
“,” and your screen should read something like “Registration Successful!” Now you can make calls to and from SIP addresses

Step 3: Get a Phone Number (optional)

You can subscribe to a virtual number to receive calls from the PSTN, but it will not be free. CallCentric, for example, offers a very reasonable “receive unlimited calls” plan for only $5.95 per month. You can set up a call rule, or “call treatment,” as they like to say, to forward to your SIP address.

Calls to SIP addresses are only limited by how many people use SIP. As we see more people using smartphones and IP phones, it’s likely that SIP addresses will be as common as phone numbers over time.

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