Calls Anywhere in the World from a Mobile App

Using a Drimsim SIM card and a virtual eSIM card, travelers can stay connected anywhere in the world. Thanks to the integration of Voximplant functionality into the mobile app, customers can make and receive Internet calls while the signal runs even on a weak connection.

First of all, it was important for us to select a partner who offered a convenient SDK for mobile platforms and a powerful API. This allowed us to rapidly set up the integration and launch new functionality that provides the most convenient calling options for our traveling customers. I would also like to note the awesome technical support service as these guys promptly respond to any request, help find a solution and – what’s really important – look for it with you for as long as it takes, even if the issue turns out to be quite challenging.

Sergey Redkov
CEO, Drimsim


Poor call quality when there is an unstable signal

In each country, the company has partner operators who provide network coverage in their territory. When a user enters a country, the SIM card pinpoints the location and selects the local operator from the list wired into it.

Calls between users used to be carried out via GSM communication, the use of which significantly increased the cost of calls. Moreover, good sound quality requires a stable signal, and not all operators are able to provide high-quality communications anywhere in the country.


VoIP calls

The integration of Voximplant SDK into Drimsim's IOS/Android customer app solved the problem of sound quality in the event of an unstable connection. With the help of VoIP technology, customers can make and receive Internet calls. A script written on the platform receives requests to initiate a call, after which Voximplant connects two users via a SIP trunk.  

By dialing a number or selecting it from the contact book, the customer can see how much a one-minute call will cost. The app also allows you to rent several phone numbers, for example, linked to different countries, and choose the most profitable option for each specific call.

How it works


Tools for rapid application development

Phone Numbers

Business phone number purchase


Trouble-free calls anywhere in the world

The main result of the integration is a new level of call quality. The company can now provide its customers with a stable connection anywhere in the world and is less dependent on the level of partner services. What’s more, calls have become much cheaper for end users.

Calls Anywhere in the World from a Mobile App

Drimsim is a universal SIM card and free travel app. The company provides the best prices for fast internet and calls around the world. The Drimsim SIM card, which appeared on the market in 2014, is used by hundreds of thousands of subscribers. The company partners with over 400 telecom operators, including Vodafone, T-Mobile, and Movistar/Telefonica.



Employee count


Project start date




Automation area

Online Calling Services