iPhone users need carrier authorization to enable hotspot.
Some users whose carrier does allow tethering but does not have a current partner agreement with Apple may have been inadvertently affected by the changes. Most, however, appear to have been abusing the function enable Personal Hotspot without paying additional fees.
“abusing” (sic) without paying additional fees?
Users are already paying for the data between the cellular antenna and their iPhones, that is what the carrier charges for. Why in earth would users pay an additional fee to forward data from the iPhone to a computer ?
Think about this: Alice wants to know which beer Bob wants to drink, Alice calls Bob but, he is taking a shower, so Dave picks up the call and asks Bob which beer he wants, Bob replies “XX Lager”. Dave who is speaking with Alice on Bob’s iPhone says “XX Lager” to Alice.
Should Bob pay an additional fee to his carrier for Dave passing the voice?
Do carriers also charge for voice forwarding ?
This is what Apple says:
Personal Hotspot lets you connect your computers and devices to the Internet using the cellular data connection on your device.
To use this feature, enable Personal Hotspot on your cellular data plan. Contact your carrier for information and pricing.
Pues tuve la oportunidad de asistir a la Escuela de Modelación y Métodos Numéricos este verano en el CIMAT.
Aquí están mis notas
Modelación de Sistemas Biológicos
Scheduling Parallel Distributed Systems
Y la foto grupal
Back in my days as university student, one of the most important concepts in the classes “Project management” and “Investment projects evaluation” was the ROI. With WhatsApp saying To handle 50 billion messages a day the focus is on making a reliable system that works. Monetization is something to look at later, it’s far far down the road.  and Zuckerberg saying Simply put: we don’t build services to make money; we make money to build better services. in the IPO letter, it is clear that not everything is about money.
“Steve’s talked about the goal of Apple, and the goal of Apple is not to make money but to make really nice products, really great products”, said Jonathan Ive .
Yes, not everything is about money, money doesn’t have real value, money shouldn’t be necessary…money shouldn’t exist in the first place
Other unrelated but interesting parts on the WhatsApp architecture article:
– In 2011 WhatsApp achieved 1 million established tcp sessions on a single machine with memory and cpu to spare. (Wow!)
– Ejabberd in FreeBSD. (I played with that!)
-32 engineers, one developer supports 14 million active users. (Good people is worth)
 Inside Apple, Chapter 3. Adam Lashinsky