Our First Impressions of IP Telephony on the 4G Yota LTE Network

    As many already know, on May 10, Yota launched the LTE network in Moscow. Over the past 2 days, a huge amount of negative emotions fell on the company about the poorly thought out organization of the transition, replacement of equipment, quality of service, etc. But at the same time, many users who managed to get the coveted “whistle” or an updated router on time and connect to the network rub their hands and enjoy the rather high (in the wireless network segment) Internet access speeds. We would like to leave aside the moral and ethical aspects of customer service and see what we are currently observing on the network and raise a number of topical issues about the additional IP-telephony service on the Yota network. Moreover, Yota itself asked to evaluate the performance of its network. Well, let's try.

    In order to understand what awaits us in the future, it is always useful to turn to history. A few words about how IP-telephony worked on the WiMAX network.

    For us, as a company engaged in voice services and the provision of communication services, cooperation with Yota began back in 2009. We were one of the first VoIP telecom operators who, in accordance with an agreement with Yota management in June 2009, began selling Ready-to-Run RTR solutions for small businesses, which included a router with already connected phone numbers - it was enough plug the router into a power outlet, insert the telephone into the jack and you could have unlimited internet and a telephone at a very attractive price. For many companies that were under the monopoly control of “pocket” telecom operators in various business centers, such decisions came in handy when there were sharp cost reductions in the midst of the crisis. Pre-configured routers left us like “hot cakes”.

    In July 2009, we were able to convince Yota that it was necessary to prioritize traffic for voice services, that is, use QoS. If one of the clients began to actively download something during a telephone conversation through a router, this was reflected in the quality of the conversation. After lengthy experiments with technical services and two-way “fine-tuning” of equipment, Yota turned on QoS - the channel width for telephony was about 160 Kbps. This was enough for two simultaneous telephone conversations in the G711a codec, or about four conversations in the G729a codec. In practice, we had several servers — some of them were “tied” to QoS (by IP addresses), and some of them we did not include in this process, because sometimes clients needed more than 4 conversations. In this case, a separate router was placed under them,

    However, in September 2009, there was such an influx of subscribers that the network already stopped physically managing, Yota was forced to disable QoS, citing the fact that this creates an additional load on their network. As a result, many customers experienced some inconvenience due to reconfiguration of equipment on the Yota network. As a result, personal work was carried out with each client - some customers reduced the number of lines, installed amplifying antennas for some, built their own channels somewhere, and agreed with other operators on compromise solutions over the channels, but we were able to save customers and their loyalty. And we are still successfully working with many.

    Realizing that additional services (in particular, voice) can bring additional benefits to the company, Yota in the fall of 2009 announced the Cosmos device to provide telephone communications to all its customers. We already understood then that at this level of network development, this is unrealistic. And so it happened - the company quickly turned off this project.

    Over time, the situation returned to normal, and we resumed connecting customers in 2010. They did this only after a preliminary three-day test on the client’s equipment - not everywhere the network was with acceptable quality parameters, since IP-telephony requires not only a high download speed, but a good return channel.

    In February 2012, we were pleasantly surprised by the opportunity to resume closer cooperation and give a second life to our RTR solution. One of the first to send a request to replace a router with built-in telephone ports. They brought it to us exactly on the 10th day at 12 noon. About the dialogues that preceded the delivery, couriers do not want to remember. But this is not about that.

    So, we set up accounts for telephone ports, turned on the telephone. With a very weak signal level (one lamp indicating the signal level on the router), the channel speed turned out to be about 6 Mbit / s at the input and about 5 Mbit / s at the output. For a start, not bad. Having made the first telephone conversation in the G711a codec, we noticed that during long conversations a small echo periodically occurs. We included the Linksys SPA303 IP phone in the router - the echo was gone, the quality improved significantly. Conclusion - the echo cancellation function in the router is implemented with some flaws. Then we decided to try the G729a codec. The quality of the conversation was much higher - no extraneous noise, echo. When talking for more than 10 minutes, there was not a single interruption or loss of words. It even surprised and alerted us a little - all is well so far. The average network latency was 40-60 ms. Compared to 120-150 ms in a WiMAX network, we consider this an extremely good parameter.

    On the morning of the 11th, of course, the router demanded a link in your account. Tied to a free tariff plan - 64 Kbps. The quality of telephone communication even through such a channel did not differ from yesterday. Not a single loss of registration on our servers - on WiMAX I had to set shorter intervals, otherwise the accounts simply “hung up” and the incoming connection did not work periodically. In LTE, this is not observed. Everything is pretty even and stable. Considering that telephony did not work at all on WiMAX in the room where the test took place, such tests for LTE inspire reasonable optimism. Today, many customers who previously sat on WiMAX asked for help in reconfiguring their newly activated equipment - so far there has not been a single negative review, all customers have our telephony.

    According to our feelings, QoS is not included at all now. With active downloads at the time of the conversation, although there are no obvious interruptions, as it was in WiMAX, some artifacts still appear. And the LTE network turned out to be very sensitive to the movement of the router - at the slightest movement or touch, the connection begins to be interrupted.

    There are fears that a situation similar to what happened in the spring of 2009 may arise - the network operates at rather high speeds, apparently due to the small number of active subscribers. Even with a weak signal level, the network allows you to work comfortably and receive various additional services, such as IP-telephony and video calls.

    In connection with the rather good results of the first tests of IP-telephony in the LTE network, I would like to ask Yota several questions:
    1. Will QoS be implemented for various types of traffic or will the principle of network neutrality be maintained?
    2. At the moment when Yota launches its own voice services (and they will, there is no reason to doubt that), will similar services of other operators intentionally be blocked?
    3. What is the current load on the network - is it more or less than the one that was in WiMAX?

    PS For users who connect via LTE routers, we propose to make a separate tariff plan with free connection of a two-channel number in the code (495) or (499). And now we are ready to provide everyone with test credentials for the opportunity to test IP-telephony services on the Yota network.

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