Disappearing airtime in South Africa may be caused by Android glitch

An issue of “disappearing airtime” on the Cell C, Vodacom, and MTN networks that MyBroadband recently discovered may be due to an issue with Android.

South African cellular subscribers often complain about their airtime or data balances depleting inexplicably and we regularly conduct tests to determine whether airtime is truly depleting on its own.

The outcome of these tests can help indicate several things, including:

  • Whether mobile network operators are abiding by ICASA regulations on out-of-bundle data billing.
  • Whether there is a technical issue causing airtime to be depleted while the device is connected to Wi-Fi or when the mobile data connection is turned off.
  • Whether airtime is being drained through illicit means, such as rogue WASPs.

In March 2020, we found that in two days, our test devices had consumed between 3MB and 9MB of data in the background while “idling”. These devices only had the default apps installed and brand new prepaid SIMs were used to perform the tests.

This idle background data usage was mostly attributed to Google Play Services.

We used four identical devices for our tests, each with a prepaid SIM from one of the four major mobile network operators in the country: Vodacom, MTN, Telkom, Cell C.

With Wi-Fi disabled on all of our test devices, we found that these small amounts of data resulted in airtime “disappearing” from the MTN and Cell C test SIMs.

MTN, Cell C, and Vodacom explained at the time that this was expected behaviour and well within ICASA’s regulations on out-of-bundle billing.

Disappearing airtime with mobile data turned off

In October 2020, we repeated the experiment and found that airtime was now “disappearing” on Vodacom and Cell C. Airtime was no longer disappearing on the MTN network.

Repeating the test with mobile data disabled on all four devices yielded extremely curious results: the Vodacom and Cell C SIMs were still losing airtime.

Vodacom’s response to our queries on the matter provided details that were even more curious.

No longer was the data depletion as a result of Google services such as “connectivitycheck.gstatic.com”. Instead, data was being routed to resources which belong to Amazon, HP, Time Warner Cable, Verizon, China Telecom, and MIT.

Disappearing data and LTE handling on Android

When MyBroadand asked MTN about the disappearing airtime issue and whether it is related to a court case against Google in the United States, the network operator suggested that the issue may be to do with the way our test devices handle LTE data sessions.

Airtime disappearing despite mobile data being switched off on the device is reminiscent of a problem MyBroadband detected on the MTN network back in 2017, which the company traced to an issue with LTE session handling at the time.

“This problem exists when it comes to LTE sessions,” explained the executive for corporate affairs at MTN SA, Jacqui O’Sullivan.

“The bearer’s session is not torn down when switching off mobile data on the handset, meaning you could potentially still be charged for a small portion of traffic.”

O’Sullivan said that this was meant to be addressed by a software update from phone manufacturers, which would terminate the bearer session when a subscriber switches off mobile data while on LTE.

MTN confirmed that to-date, the issue is fixed on Huawei devices.

“For LTE, this is how the technology works,” O’Sullivan said. “It provides an ‘always connected’ experience. We had to put the fixes in place to mitigate this flaw until all phone manufacturers apply a fix.”

It is not immediately clear whether the same LTE session handling bug that hit MTN is what caused the disappearing airtime in MyBroadband’s tests during October 2020.

The evidence that seems to contradict this possibility is the fact that Vodacom saw traffic destined for Amazon, HP, Time Warner Cable, Verizon, China Telecom, and MIT from our test device.

Google sued over disappearing airtime

The Register recently reported that Google is facing a lawsuit in the United States because of the large amounts of data Android appears to consume in the background.

According to the complaint, they tested a new Samsung Galaxy S7 phone and found that it “sent and received 8.88 MB/day of data, with 94 per cent of those communications occurring between Google and the device.”

The device was signed in to a Google Account and left on its default settings to idle with all apps closed and without a Wi-Fi connection.

It allegedly transferred data to Google about 16 times an hour, or approximately 389 times in 24 hours.

The Register noted that assuming only half the data measured on the device is outgoing, that means the device sends around 4.44MB per day or 130MB per month.

This is in-line with the upper end of MyBroadband’s own measurements of 9MB over two days.

The lawsuit aims to recover the “fair market value of the data allowances Google has misappropriated, as well as the value of the personal information which Google has thereby acquired”.

Vodacom and Cell C respond

MyBroadband asked Vodacom and Cell C whether the lawsuit against Google in the United States has anything to do with the disappearing airtime detected on their networks.

Vodacom said: “We are not aware of any relevance from a Vodacom perspective.”

Cell C said it will continue to monitor the case as it unfolds.

“We cannot comment as to whether there is a direct relationship between the lawsuit and the behaviour of Android devices while connected to Wi-Fi,” Cell C stated.

Google did not respond to requests for comment.

Now read: What to know before importing the Google Pixel 5

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Disappearing airtime in South Africa may be caused by Android glitch