Let me post an experiment that I have started in case others would like to try it. Frustrated by the same problem others have been describing here and with no ability to look at the cellular packets, I created a setup where at least I could monitor all of my iPhone’s usage while on a wireless network. Skip down below to see the setup and results so far.
First, my problem: 2 iPhones demonstrating similar behavior as those in this forum but I will focus just on one. This iPhone has an unlimited domestic data plan grandfathered in with AT&T and a 125MB international data plan. The last two times we were in the Caribbean, we got overage notices and then got shut down by AT&T (which was probably good since the bill had gone over $1000 each time).
In looking at the billing statement, we had single 350MB line items on the bill almost every day. I will spare you all of the details of the conversations that I have had with AT&T since they have gotten nowhere. I do understand that the 350MB line item was an accumulation of all of the usage for the day and that even though it said “sent”, it was a combination of both.
For the record, I do have an MCell but that should be out of the equation when we are in the Caribbean.
Second, my experiment: Though I understand that some applications on the iPhone will send more data when connected over wireless than when connected over cellular, I believe that if you watch the iPhone’s packets while connected over wireless, it will pretty much contain at least all of the data packets that would be sent over cellular. So I did the following for my setup:
- ) Set up my Mac for internet sharing. Doing this, I had wired Ethernet coming into my Mac and it provided a wireless network different from that in my home.
- ) I set the iPhone to use this new wireless network and had it as the only device on it.
- ) I ran Wireshark, a free packet analyzer, on my Mac on had it capture all packets that went over this new wireless network.
Third, my early results: Wow, there was a lot of activity! In capturing data for 18 hours, there were 461K packets. Scanning them quickly, here are the most common IP addresses and who owns them:
111.221.77.146 | Microsoft |
173.194.68.109 | Google |
173.194.73.104 | Google |
173.194.73.106 | Google |
173.194.73.147 | Google |
173.194.73.99 | Google |
207.171.163.25 | Amazon |
209.85.225.108 | Google |
74.125.45.109 | Google |
74.125.45.109 | Google |
The biggest offender seems to be 173.194 group belonging to Google, particularly 173.194.68.109 and it seems to be primarily outgoing. A large number were 1484 bytes in length.
Though I don’t understand why either Amazon or Microsoft are in the mix, I concentrated on Google. The phone used IMAP for gmail so I began investigating that. To see if there was a difference, I switched it to use Exchange as described on Google’s setup page and it did not seem to make a difference in the traffic.
One of the first interesting things I noticed is that if I am reading email on my Mac, when I select it and it goes unbold to designate read, the unread count on my phone is updated in less than a second (impressive). However, in order to pull this off, 27 packets are sent between my iPhone and Google, including two from my iPhone that are 1484 bytes each. If I delete a message on my Mac, it is about 50% worse.
If on my iPhone, I look in a mail folder that has only three mail messages, 50K of data is sent to my phone.
More experiments will eventually follow when I have time.
Feel free to comment on the validity of this experiment or post your results from a similar experiment.