SIP Calling: What Is It & How Does It Work?

SIP calling is a method of making voice calls through a SIP channel or SIP trunk. It establishes a virtual connection using the Session Initiation Protocol (SIP), eliminating the need for traditional analog phone lines. Moreover, this protocol not only supports real-time voice communications but also integrates video conferencing, instant messaging, and other multimedia applications.

Essentially, SIP calls use Voice over Internet Protocol (VoIP) technology to efficiently route your calls over the Internet.

SIP calling works by replacing traditional phone systems like Private Branch Exchange (PBX) and Primary Rate Interface (PRI) lines with virtual SIP trunks that connect directly to the Public Switched Telephone Network (PSTN) via an internet connection.

Here’s how SIP call flow works:

1. Call Initiation: The call originates from a SIP-enabled device (hard phone, softphone, PBX).
2. PBX Routing: The call is processed through an on-premise or cloud-based PBX.
3. Internet Transport via ISP & NNI: The call is transmitted over the internet (either public or private) via the Network-to-Network Interface (NNI).
4. SIP Provider Routing: The call reaches the SIP provider’s network and is routed to the recipient’s carrier.
5. Recipient’s Device Compatibility: The call directly reaches the recipient’s SIP device. If they use an analog phone, an Analog Telephone Adapter (ATA) converts the signal.
6. Call Completion: The recipient answers the call, and the connection is established.

SIP calls save cost, offer more scalability, flexibility, and advanced features compared to traditional landlines.

• Cost-effective: SIP calls route calls over the internet, offering low rates and minimizing hardware investments.
• Unified Communication: SIP integrates voice, video, messaging, and conferencing into one platform.
• Easy Scalability: The SIP calling system scales up or down just by adding or removing channels as needed.
• Excellent User Experience: SIP calls deliver high-quality audio and reliable connectivity.
• Call Management Features: SIP providers offer advanced business communication features.
• Reliability and Quality: SIP Protocols monitor latency and packet loss to keep your calls clear.

To set up SIP calls on an iPhone, download the SIP app, get SIP credentials, configure the SIP app, and set up incoming and outgoing calls.

• Step 1: Download a SIP App: Install a SIP-supported app like Zoiper, Bria, or Linphone from the App Store.
• Step 2: Get SIP Credentials: Obtain your SIP username, password, and server address from your service provider.
• Step 3: Configure the SIP App: Open the app and enter your SIP account details.
• Step 4: Set Up Incoming and Outgoing Calls: Configure the app to handle calls over Wi-Fi or mobile data.
• Step 5: Test the Connection: Make a test call to confirm that both incoming and outgoing calls are working as expected.

To set up SIP calls on your Android device, open the Phone app, navigate to the settings, add your SIP account details, and activate SIP calling.

• Step 1: Open Phone App: Go to the dialer and tap the three-dot menu.
• Step 2: Go to Call Settings: Select "Settings" > "Calling Accounts" or “Advanced Settings”> "SIP Accounts" (varies by device).
• Step 3: Add SIP Account: Tap “Add Account” then enter your SIP username, password, and server details.
• Step 4: Enable SIP Calling: In the ‘SIP settings’, set your phone to "Receive Incoming Calls".
• Step 5: Test the setup: Call a SIP number or another VoIP user to confirm that it works.

Be mindful, not all Android devices support SIP natively. In this case, you can use third-party apps to set up SIP on Android.

Here’s how to activate SIP on Android using third-party apps:

• Step 1: Download a SIP App: Install Zoiper, Linphone, or another SIP provider from the Play Store.
• Step 2: Get SIP Credentials: Obtain your SIP username, password, and domain/server address from your VoIP provider.
• Step 3: Configure the App: Open the SIP app, go to the ‘Account settings’, and enter your SIP details.
• Step 4: Allow SIP Calls: Enable calls over Wi-Fi or mobile data (Check the app setting for network preferences).
• Step 5: Make a Test Call: Ensure the setup works by calling another SIP number.

SIP calling leverages the Internet for high-quality voice, video, and messaging services. This not only saves the cost, but also offers flexibility by allowing you to adjust your phone system based on the changing demands of your business. Moreover, with advanced encryption and authentication, SIP is a more secure business phone system than traditional phone lines.
 

No, SIP calling and Wifi calling are not the same. While SIP calling uses the SIP protocol to make calls over the internet via a VoIP provider, Wi-Fi calling is a carrier feature that allows you to make calls over Wi-Fi using your mobile without needing an SIP account.

SIP calling is used by businesses as a cost-effective alternative to the traditional phone system. Additionally, it comes with additional features like call forwarding, conferencing, multimedia connection, and more.

Yes, a SIP call needs an internet connection because it transmits voice data over IP networks instead of traditional phone lines.

SIP calls between users on the same SIP network are usually free. However, calls to external phone numbers (such as landlines or mobile numbers) incur costs. The exact cost depends on your SIP provider.

A typical SIP voice call using the G.711 codec requires roughly 90 kbps of bandwidth, while using a compressed codec like G.729 requires around 30–40 kbps per call.