Mastering Linphone Customization: A Comprehensive Guide to Avoiding Common Pitfalls

In the realm of open-source solutions for developing voice, video, and chat applications, Linphone stands out as a top contender. While a comparative analysis of Linphone versus other platforms can be explored in a separate article, this piece focuses on the common pitfalls encountered during Linphone customization. These mistakes are often made by both developers and business people who hire freelancers for the job. Here, I outline these common errors to guide both freelancers/developers and business stakeholders towards a smoother customization process.

Essential Considerations for Linphone Customization

1. Push Notifications Are Mandatory

One of the biggest oversights in Linphone customization is neglecting push notifications. This mistake usually comes to light very late, sometimes even after the application is published on app stores. On the latest Android and iOS platforms, there is a restriction that prevents VoIP applications from accessing the internet when the app is in the background or when the phone is in sleep mode. This results in the VoIP application becoming unregistered from the SIP server, causing it to miss incoming calls unless manually activated. Although Android has a background mode option, it is power-intensive. For iOS, push notifications are the only viable solution. A detailed guide on installing and implementing the Push Notifications via Flexisip Push Notifications Server can be found here.

2. Disable ‘Background Mode’ in Android Linphone

In the advanced settings of the Linphone application, there is an option called “Background Mode” which keeps a notification to indicate the app is alive. However, enabling this is not recommended by me for two reasons. Firstly, it doesn’t guarantee that calls will always come through, as the operating system can override this setting to optimize battery life. Secondly, it significantly drains the battery. Therefore, push notifications remain the most reliable option.

Screenshot of Background mode from Linphone Android

3. Enable G729 Codec

The default Linphone application source code does not include the G729 codec. To enable this, you need to compile the lib-linphone SDK. More information on how to compile and use this SDK after enabling G729 can be found in another article of mine here. G729 is a preferred codec among carriers due to its low bit rate (8kbps), which conserves bandwidth and supports more calls, ultimately saving costs. It also provides good audio quality in low bandwidth conditions.

4. Adopt a Least Change Strategy

Minimizing changes is key to reducing bugs in the well-tested Linphone application. Linphone’s source code is structured in a way that allows for easy customization through configuration edits. Therefore, choose customizations wisely to maintain a balance. Stick to standard customizations that don’t require extensive code changes — focus on modifying images and configurations instead.

5. Publish Applications Yourself

Once customization is complete, upload the code to your repository. Then, pull the repository into Android Studio, where the Gradle scripts will automatically sync and build it. Follow the standard steps to create your private keys and publish the application on app stores yourself. This practice prevents your private keys or secrets from being compromised, thus enhancing security.

6. Respect GPLv3 License

Ensure that your source code is published publicly on GitHub to comply with the GPLv3 license.

7. Hire a VoIP Consultant

Hiring an experienced VoIP consultant is preferable to engaging an unknown freelancer from a freelancing site. While it may seem cost-effective initially, it can lead to higher costs in the long run. A domain expert with extensive experience in SIP servers and SIP proxies (such as Freeswitch, Opensips, Flexisip, and others) is better equipped to handle complex issues like debugging call drop-offs or resolving NAT issues. A VoIP consultant can provide quality application development and ongoing maintenance.