Automobile race and service testing

Yota is actively preparing for a full-scale launch of a wide commercial operation as a mobile operator. Yota voice communication services are already available throughout the country in limited commercial operation mode - and as part of this testing, our employees and a limited number of subscribers check the configuration of network elements in different regions, as well as the correct operation of the provided Yota services.


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Echo of Moscow radio station was the first to take part in testing the new federal mobile operator Yota within the framework of the road history Road Run . A group of famous journalists and radio hosts traveled by car to nine cities on the route Moscow - Kazan - Kirov - Perm - Yekaterinburg - Ufa - Orenburg - Samara - Saratov - Moscow, during the run a number of meetings were scheduled with Echo of Moscow listeners from radio broadcasting cities . We provided all the participants with Google Nexus 5 smartphones with unique Yota SIM cards , and they regularly gave feedback.



Below is a story about how many days of testing took place and what difficulties and technical peculiarities Yota specialists faced.

The case at the border

During the trip, journalists regularly wrote travel notes on the social networks with the hashtags #echoroad and #yotamobile, laid out photos. The only channel of communication for this purpose was the mobile Internet. The expedition started from Moscow, at first there were no difficulties, but the mobile Internet was gone on the border of the Kirov region and Tatarstan. Since we were unable to diagnose the problem remotely and did not want to distract journalists from their immediate work, it was decided to send a group of technical specialists from St. Petersburg to help. At the same time, they had to carry out a thorough check of the work of the services throughout the rest of the route, thereby speeding up the scheduled testing in these regions. Just a day, two crews were organized, who joined to test and support the Echo of Moscow rally. One crew arrived in Perm, the second - in Yekaterinburg, the next city on the route.





The cause of the problems was clarified on the spot - it turned out that the analysis of the range of Yota SIM cards was not registered in the packet network (PS domain). After the IMSI Yota range was registered in the PS domain of the Ural branch of the MegaFon network, the mobile Internet started working again.

Technical Reference : when a mobile phone is connected to a cellular network at the base station level, it is registered in two networks: a CS domain (Circuit switch, voice communication) and a PS domain (Packet switch, data transfer). This is necessary for voice calls and data transfer. And in both domains, it is necessary to register the analysis of the IMSI range of each mobile operator.

Journalists regularly sent us the results of measurements of the speed of the mobile Internet - and except for the described case, he was present throughout the route, without any pronounced bursts.

From dusk to dawn

From the point of view of most people, becoming a mobile operator is quite simple, only expensive. It is enough to stretch more cable, install base stations more often. In fact, this is a complex and complex process, and it depends not only on the actions and efforts of Yota. There are a number of tasks that must be solved by other players in the telecom market. Due to the large number of different operators, it is not easy to control the actions of each partner.

Technical Reference : as a new operator Yota has its own number base. To ensure the correct operation of our services, other mobile and fixed communications operators must correctly register call routing. If operator “A” does not do this with regard to the number base of operator “B”, then in this way it worsens the service for its own subscribers. Because they will not be able to make and receive calls from subscribers of operator "B".

The number base of each operator is limited to the DEF codes assigned to it (a three-digit number following the country code (+7 xxx *** - ** - **). For many operators, the DEF code is tied to a specific region. However, mobile operators have one the same def code is used in different regions.

Between telecom operators, voice interconnection points are organized. Through these interfaces, voice call routing is configured. And Yota faces a very time-consuming task of coordinating routing registrations with a large number of telecom operators across the country.

Shortly after the start of the expedition, Echo of Moscow journalists found that some stationary caller numbers were incorrectly determined from 22 to 10 hours. That is, instead of the Moscow number of the radio studio from which their colleagues called, other numbers were periodically determined.

It turned out that this is a problem on the side of the landline provider that the Moscow radio station works with. In his routing settings, the DEF-code Yota was mistakenly identified as belonging to St. Petersburg. At night, the long-distance call was connected via an alternative St. Petersburg provider, which led to an incorrect determination of the calling number. Routing was quickly corrected by them, after which caller numbers were determined correctly.

Proactive fix

Technical Reference : 2G / 3G networks consist of a CS-domain and a PS-domain. The LTE network (4G) consists only of the PS domain, that is, it is used exclusively for data transmission. Currently in Russia, voice communication within LTE networks (VoLTE, Voice over LTE) is not certified by government agencies. Therefore, a transitional CSFB (Circuit switch fall back) technology is used. So that the subscriber who is in the LTE network can make / receive voice calls, switch to the 2G / 3G network, and vice versa. The procedure when a subscriber with a priority is registered in a 4G network, but the system can switch it to 2G / 3G, is called a combined attach (combined registration). This is one of the components of the CSFB.

Only once during two weeks did one of the crews who tested the connection encounter incorrect work on the 4G network in Ufa. Yota specialists analyzed the traces between the MME and the MSC (the exchange of signaling messages between the 4G and 2G / 3G network elements). It turned out that the CSFB procedure was configured incorrectly, a combined attach failed. That is, the subscriber was registered in the 4G network, but it did not bind to the CS-domain in 2G / 3G. Thanks to the well-coordinated work of Yota and MegaFon specialists, this failure was quickly eliminated. Therefore, the journalists of "Echo of Moscow" did not even face him.

This is another example of what a complex and unique task for the Russian telecom market is Yota, deploying a full-fledged MVNO throughout Russia. Indeed, as a 4G network, Yota uses its own dedicated segment under its carrier name, and 2G / 3G networks are provided by MegaFon. That is, all Yota-devices simultaneously operate in two different carrier networks. This is not a typical service implementation scheme. There are less than five such networks in the world. And Yota has to overcome many organizational and technical difficulties to ensure high-quality and uninterrupted operation of its services.

Conclusion

Yota specialists returned home to St. Petersburg, and journalists returned to Moscow, where we met them together with colleagues. Thanks to the rally, Yota conducted very important user testing of its services. Thanks to the well-coordinated work of all the participants in the testing, deficiencies that could affect subscribers were found and eliminated. In addition, we made sure that Yota is ready for launch into a wide commercial operation.





Preparations for launching into wide commercial operation are greatly complicated by the uniqueness of the case - for the first time in Russia, Yota is building a federal cellular coverage with a roaming-free space based on the combined Scartel and MegaFon networks. Not a single player in the Russian telecom market has yet solved this problem. Therefore, Yota uses every opportunity to assess the quality of communication for its users.

We invite all interested journalists and bloggers to take part in the joint testing of the services of the mobile operator Yota. Send your questions and suggestions on testing to press@yotateam.com. In the summer of 2014, the issuance of SIM-cards will begin:

• users who placed an order on the website and through the Android application
• journalists and bloggers.

A press event about the launch of the Yota operator into a wide commercial operation will be held a little later.