Vodacom disappearing airtime mystery

Vodacom is unable to explain why airtime is disappearing from its subscribers when they are connected on a Wi-Fi network.

MyBroadband recently conducted a battery of disappearing airtime tests which found that Vodacom and Cell C SIMs lost airtime while other operators did not.

The research found that despite being uninterruptedly connected to Wi-Fi over a number of days, Vodacom and Cell C SIMs incurred out-of-bundle data usage.

Vodacom and Cell C both said this data usage was the cause of the airtime “disappearing” on our devices.

However, we monitored the data usage of devices we tested, and those with MTN and Telkom SIMs reflected equal or greater mobile data figures while connected to Wi-Fi, despite not losing any airtime.

All of the data usage recorded during our disappearing airtime tests was categorised as “OS services” by our mobile app.

OS Services data usage

Our data usage monitoring app observed negligible amounts of mobile data consumption over the period despite being connected to Wi-Fi (usually less than 200kB).

This measurement was identical across all networks (except for an anomalous Telkom reading) and was attributed entirely to an “OS Services” process on each device.

Telkom was an anomaly, as despite blocking data usage by default when no data bundle is active and maintaining its airtime balance throughout the test, our data monitoring app measured 2.03MB of data usage on the SIM – all of which was also categorised as “OS Services”.

The data monitoring app also showed constant and stable Wi-Fi usage throughout the period of the test for each SIM.

Below is the measured “OS Services” usage for each SIM over the test period (accounting for the entirety of the mobile data usage on each device) compared with the airtime depleted on each SIM:

Network “OS Services” usage Airtime lost
Telkom 2.03MB R0.00
Vodacom 0.2MB R0.23
MTN 0.2MB R0.00
Cell C 0.1MB R0.13

The airtime balances for each new prepaid SIM as recorded over the test period are shown below:

Airtime balances over the test period
Network 1 Oct 2 Oct 5 Oct
Vodacom R10.00 R9.93 R9.77
MTN R10.00 R10.00 R10.00
Telkom R10.00 R10.00 R10.00
Cell C R10.00 R10.00 R9.87

The airtime balance did not deplete on MTN or Telkom – which means that if this OS Services process is the cause of the “disappearing airtime”, only Vodacom and Cell C charged for it.

It is unclear whether this discrepancy in airtime depletion is due to the zero-rating of these processes by MTN and Telkom.

MyBroadband asked Vodacom and Cell C for a comprehensive overview of the mobile data usage and why we did not see similar billing from other networks.

Cell C responds

Cell C told MyBroadband that it has reviewed the charges and confirmed that the SIM was correctly charged for data traffic.

The network also said the traffic generated and charged was not related to establishing or maintaining connectivity to its network.

“All traffic charged relates to Google public IPs,” it said. “We cannot comment on the source of the  traffic on the device – i.e. background app, background OS (Android), or other.”

Cell C said it could not comment on why MTN and Telkom did not incur the same charges despite reflecting the same “OS Services” background data usage.

“We cannot comment on the data usage settings, other networks’ charging policies on the devices, or any potential traffic that may or may not have been generated to other networks during the test,” Cell C said.

Cell C provided MyBroadband with a list of IPs related to the data charges, which comprised the following:

  • connectivitycheck.gstatic.com
  • (Google)
  • play.googleapis.com
  • (Google)

“These destinations are all chargeable and would consume from a data bundle. If no data bundle is applied, the charges are subject to out-of-bundle charging,” Cell C said.

Vodacom responds

Vodacom was unable to confirm the cause of the out-of-bundle data depletion shown in our tests relative to other operators but said it was testing to see if it can replicate the phenomenon.

Like Cell C, Vodacom found that the data usage was incurred primarily by Google Services – specifically the same “connectivitycheck.gstatic.com” URL reflected in the Cell C data usage logs.

“We are running tests similar to the MyBroadBand setup to see if we can replicate the same conditions,” Vodacom said.

“In the interim, it seems as if the issue relates to Android devices that use data across mobile while connected over Wi-Fi.”

Vodacom said it puts a Data Limit Lock (DLL) on a new SIM and will allow the SIM to go OOB, using any airtime balance. Only once a bundle is purchased will OOB charges be stopped.

The operator clarified that the data was related to OOB usage (via the Google URL), and not a result of passive connection to its mobile network.

“We don’t charge data for a new device to establish a connection on the Vodacom network. The charges on this prepaid line were related to OOB data usage,” Vodacom said.

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Vodacom disappearing airtime mystery