With EW Polyphone, the operator expands the functionality of its messenger, gains a more flexible solution, and has the opportunity to develop it independently. Tcell is Tajikistan's first mobile operator to introduce its messenger for SIP-GSM calls. Tcell's subscriber base exceeds two million people, with approximately 10% actively using the Chi Gap application.

Why Tcell Decided to Change the Messenger

The operator launched the Chi Gap application over ten years ago ("Chi Gap" in Tajik means "the ability to speak"). The primary function of the operator's messenger was to make calls via the Internet, from the application to GSM numbers and vice versa. Thanks to this, Chi Gap users can call loved ones in Tajikistan from abroad without incurring roaming costs, maintaining connectivity with their usual phone number. This strategy helped Tcell retain subscribers even when they traveled abroad, continuing to generate revenue through application-based calls.

In mid-2023, Tcell opted to replace its existing messenger with a more flexible solution. The new provider needed experience launching similar applications to migrate all Chi Gap users to the new platform within a limited timeframe, minimizing disruption for subscribers.  

Eastwind presented its product, EW Polyphone, which ultimately won the vendor competition. We launched the updated messenger for Tcell at the end of December 2023.

Before replacing the solution, the Eastwind team updated the application design, making it more user-friendly and modern
 

EW Polyphone Features

EW Polyphone is a corporate messenger offering easy integration into a telecom operator's network or any large organization.

— Connects with the company's internal services such as billing, email clients, campaign managers, etc.
— Enables calling and messaging via the Internet from a mobile number.
— Supports popular messenger functions: group chats, audio and video calls, emojis, and stickers.
— Available on Android and iOS mobile platforms and Windows desktops.

Learn more about EW Polyphone

Implementation Details

The time frame for replacing the application in Tcell was strictly limited. The updated Chi Gap had to be launched before January 1, 2024, since the previous developer stopped supporting the messenger that day. To speed up implementation, the Eastwind team actively assisted in preparing the hardware site, including server installations and virtual machine setups. The project faced setbacks due to unforeseen delays in server equipment delivery. To mitigate these, we proceeded with software deployment on temporary virtual servers, with necessary integrations completed with Tcell's internal systems. Once the equipment arrived, Eastwind seamlessly transferred the configured solution, ensuring uninterrupted service for subscribers.  To log in to Chi Gap, the user must enter an SMS sent to the Tcell mobile number. However, some subscribers have been abroad for a long time and have already lost access to their physical SIM cards. If we had logged them out when we replaced the solution, they would not have been able to log into Chi Gap again.

To prevent the loss of such users, the developers transferred Chi Gap registration data in app stores from the old version to the new solution. This enabled automatic authentication upon updating the messenger from Google Play or the App Store, maintaining user access without requiring SMS verification. The updated messenger now includes video calling and SMS functionality within the application. The first function affects user loyalty; the second provides an additional revenue stream for the operator.

> 480,000 messages sent by Chi Gap users within six months of introducing new features

40% or nearly 200,000 SMS were sent by subscribers from the Chi Gap application to GSM numbers, generating revenue for the operator

Project Plans

According to the initial terms of the project, Eastwind will transfer the application source code to the operator this autumn, enabling independent development of Chi Gap. However, while establishing an internal mobile development department at Tcell, Eastwind will continue supporting the operator and the messenger. After all, our top priority is to assist clients in fully utilizing the product capabilities for successful goal attainment.

"This is our fifth implementation of EW Polyphone for a telecom operator. The team's experience allowed us to swiftly address all challenges, ensuring a seamless messenger replacement without downtime."

Anton Ageev, Head of the Computer Telephony Department at Eastwind