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Wrong Number: Why Phone Companies Overcharge For Data
MrSeb writes "A recent study (PDF) conducted by UCLA professor Chunyi Peng shows that carriers generally count data usage correctly, but those customers who commonly use their device in areas with weak signal strength or to stream audio or video are often overcharged. Peng and three other researchers used data gleaned from an app installed on Android smartphones on two different carriers. The issue appears to be in how the system is set up to count data usage. Under the current scenario, data is charged as it is sent from the carrier's network to the end user. What does not exist is a system to confirm whether the packets are received, and thus preventing charges for unreceived data. Peng demonstrated this in two extreme circumstances. In one case, 450 megabytes of data was charged to an account where not a single bit of it had been received. On the flipside, Peng's group was able to construct an app which disguised data transfers as DNS requests, which are not counted by the carriers as data usage. Here they were able to transfer 200 megabytes of data without being charged. Overall, the average overcharge is about 5-7% for most users. While that does not seem like much, with unlimited plans gone and data caps in style that could pose potential problems for some heavy data users. Could you be going over your data allotment based on data you never received? It's quite possible."
It is true, I work for a supplier of GSN nodes and most operators configure GGSN/PGW to classify DNS and TCP SYNs as free. However, this freebie is overset but charging retransmission in the telco IP network. Personal experience in comparing sent bytes vs received bytes on remote and charged bytes in CDRs. Wiresharking on Gn interfaces pointed out the origin of extra bytes in CDR. So there never is a free lunch
Resending a packet due to a missed ACK takes up air time, just like it did sending it the first time, and the carriers have no control on where the user will be. If they make their systems robust enough to move their present average packet reception rate from an already-good 93-95% to, say, 99%, this will only enable their users to move down another floor in their sub-basements, or another few city blocks, or another cubicle row deeper into the building, before the average goes back down again -- after all, wireless systems have limited range. The cost of the new infrastructure would be roughly twice that of the previous one ("increasing coverage is increasingly expensive"), and you're going to pay for the cost of the infrastructure either way in your air-time charges.
Look at it this way: Even if the company only charged for packets successfully received, it would just increase their rates by (1/0.95) - 1 = 5.3% to (1/0.93) - 1 = 7.5% to maintain the same cash flow. Plus it would have to start keeping track of the success or failure of each packet transmitted, and put that into its billing scheme. That's a database PITA I don't want, thank you very much.
Do you really think what carriers charge is how much it actually costs to send a text message?