Powering the leading Taxi App in Japan: How GO Delivers Seamless Mobility with Twilio Programmable Voice

Twilio Programmable Voice delivers high-quality, scalable communications—making taxi journeys safer, more reliable, and more reassuring.

Making the moment you meet your taxi more certain and comfortable. 

At GO, Twilio powers the in-app calling that seamlessly connects users and drivers. In 2024, GO introduced a breakthrough feature enabling direct voice calls between taxi operators and driver terminals, a move that became a gamechanger to the customer experience. We spoke with the team behind the scenes to learn how these innovations support a frictionless mobility ecosystem.

Eliminating the "Can't Find Each Other"Problem Between Users and Taxis

GO Inc. operates under the mission "Unlocking the value of 'Mobility'." Centered around the taxi app

“GO” is one of Japan’s leading taxi apps, providing a wide range of mobility services across all 47 prefectures in Japan. From GO PREMIUM for luxury vehicles, GO Economy for ride-pooling, and GO BUSINESS for corporate customers, the platform is designed to modernize everyday transportation.

A primary focus for GO is ensuring that users and drivers can find each other instantly. Makoto Wakimizu, Head of Product Management Dept., explains:

"Even when a driver arrives at the pickup location, there are cases where they can't find the customer. Although the car may appear close on the map, building layouts or road structures can make it difficult for both parties to locate each other.

To solve this 'can't meet' problem, we introduced direct voice calls between users and drivers. Drivers have been able to call users since the days of predecessor services - JapanTaxi and MOV, but to further improve the experience, we developed and released two-way calling in 2024, allowing users to call drivers as well."

Reducing Development and Operations Costs with Reliability and Scalability

Tatsuya Tojima from Software Development Division, Backend Group led the server-side development and shared his experience with Twilio:

"We built the user-to-driver calling feature in about one to two months. Twilio's APIs are extremely simpleーvoice calling works just by connecting the necessary components. If we had built our own voice system, it would have required significantly more effort. We can also identify issues quickly in the console, which provides peace of mind during operations. I also heard from teammates who previously implemented driver-to-user calling that they chose Twilio for its reliability and scalability after comparing multiple services. After developing this new feature, I'm convinced that decision was absolutely right."

Designing Ul and Call Control for Handling Multiple Calls

Implementing a voice solution in a high-traffic environment requires a sophisticated UI and robust call control. Hidemune Takahashi from the client-side development team emphasized the importance of reliability:

"Our most critical responsibility was ensuring calls connected every time. While voice implementation isn't a daily task for us, Twilio’s SDK documentation and GitHub samples made the process seamless. On iOS, leveraging Apple’s CallKit alongside Twilio’s references significantly reduced our research and verification time."

However, taxi services come with unique challenges:

"GO supports multiple vehicle dispatch, so users can request two or three taxis at once. For example, a user might receive a call from Taxi A while they are already talking with Taxi B. We carefully designed client-side controls to prevent the call experience from breaking in these situations. Our goal was to ensure users could communicate smoothly with any driver without confusion."

Connecting Taxi Operators and Drivers

In 2025, GO expanded its use of Twilio to the GO Admin Console, enabling direct communication between taxi dispatch managers and drivers. Product Management Dept., Daisuke Tomomatsu explains the shift:

"Communication between operators and drivers involves more than dispatching rides. Situations range from 'I can't find the passenger' to 'I can't park at the designated spot' or 'I found a lost item in the car!’

Traditionally, this communication relied either on taxi radio systems or personal mobile phones. The latter requires manual phone operation and depends on the driver's judgment to answer. As app-based dispatch grows and more operators look to reducing or eliminating taxi radio systems, demand has increased for a safe, reliable communication method."

Development of the GO Admin Console began about a year ago.

"We also used Twilio to build voice calling in the Admin Console. Assuming hands-free communication while driving, we tested calls in actual taxi vehicles-doors open, air conditioning at full blast, and heavy road noise.

We were concerned we might need dedicated microphones, but Twilio's call quality proved highly stable. Even in noisy environments, we achieved clear audio without additional hardware. The feature is now sold as a paid option, and we've received no complaints on audio quality."

Tatsuya Tojima from Software Development Division, Backend Group:

"GO uses an internal platform to rapidly develop and operate microservices. For voice, we built a shared internal calling platform integrated with Twilio and reused it across multiple domains. This centralized management of call processing, logs, and call states significantly improved both development and operations efficiency.”

Tatsuya Tojima also shared feedback from engineers on the front lines:

“Engineers on the vehicle-side have also praised the system, noting that the 'APIs are straightforward and easy to handle' and 'call lifecycle management is easy to understand.' On Android, they were able to implement everything using only the Twilio SDK, without needing integration with additional OS libraries. With the extensive samples provided and high call quality, the overall operation has been very stable. 

While we built our own call UI, integrating it with the native UI was not difficult. The process is self-contained—simply customizing the name displayed on incoming calls, displaying the UI upon receiving an FCM (Firebase Cloud Messaging) notification, and calling the SDK. I’ve also heard that the high degree of flexibility was a major draw—for instance, using TwiML to easily enable calls even to parties without a phone number."

Toward Better Connections

Looking ahead, Makoto Wakimizu, Head of Product Management Dept., shares GO's vision:

"Twilio offers many products beyond Voice APIs. We want to deepen our understanding of these capabilities and explore how they can be applied. If there are ways to enable drivers, operators, and users to communicate more smoothly through calls and integrations, we're eager to adopt them."

 Behind every ride, Twilio Programmable Voice is the invisible thread—delivering the reassurance of a human voice to drivers and passengers across Japan.