If I have both Wi-Fi and Cellular Data activated my iPhone 5S will restrict ALL DATA to Wi-Fi or it will use shorts amounts of data from cellular?

First, turn off WiFi Assist in Settings/Cellular.

There are several cases where the phone will use cellular data over WiFi even if WiFi assist is off:

• Notifications such as Push email, weather, stocks, etc
• Visual Voicemail
• MMS messaging
• The biggie: WiFi turns off when the phone goes to sleep to preserve battery (WiFi uses power continuously, whether data are being exchanged or not). So any apps that use background data will switch to cellular if the phone is asleep.

The simple answer is that the phone uses some cellular data even if you have a WiFi connection. It's a bit more complicated than that, however:

• Go to Settings/Cellular and scroll to the bottom. You've discovered there's a switch "Wi-Fi Assist." If this is on the phone will use cellular when the cellular signal is better than the Wi-Fi signal. This may be what your carrier is referring to. You can turn it off, however, as you did, to prevent that from happening.
• Also in Settings/Cellular you can disable any apps that you don't want using cellular data at all, like photos.
• There are a few functions that always use cellular data, even if you have a Wi-Fi connection, most notably MMS messaging and Visual Voicemail. These are carrier services, and your carrier doesn't know about your Wi-Fi connection, so it can't use it.
• Notifications and Push email notifications always use cellular data for a similar reason. However, they use very little data unless you get hundreds of notifications a day. It's only the notification that uses data; the app responding to the notification will use Wi-Fi if available.
• Probably the biggest factor is the way Wi-Fi works. iOS disables Wi-Fi 30 seconds after the phone goes to sleep (that is, the screen is off) to reduce battery drain, unless the phone is connected to power. Thus, any apps that update in background will use cellular data (unless you turn off cellular data for those apps in Settings/Cellular).

If you turn off background app refresh it will use less cellular data, but it will still use some. That's because Notifications use data, and that doesn't count as background refresh. The only way to prevent all cellular use is to turn off cellular data.

The iPhone will always connect to and use Wi-Fi when it's available. The first time you connect to the Wi-Fi network, you'll need to set it up (put in password, etc.), but then it will automatically connect the next time it's in range. When it's connected to Wi-Fi, almost all data will go through Wi-Fi, except for some features like picture messages (MMS). When the phone has no Wi-Fi available, it will go back to cellular. If the device is not staying connected to Wi-Fi, go to Settings > Cellular. Then scroll down and tap Wi-Fi Assist.

Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support

My cellphone carrier charges me for data even if I am home using wifi. My billing statement has data charges every hour for 24hours.

They claim that the iPhone chooses the best network whether wifi or cellular and uses whoever has the best connection.

Hence, if I am syncing my photos to google or iCloud at home, there is a chance that iPhone sometimes uses cellular data instead of wifi.

I'm currently using iPhone 6s and my Wifi Assist has always been off.

Is my carrier telling the truth or are they screwing me with the data billing?

There are 2 models, WiFi only, and WiFi+Cellular. The WiFi+Cellular model has a SIM, just like a cell phone does, and can use cellular data, just like a cell phone does, in addition to WiFi. However, it cannot make phone calls. See my post above (Re: If I have both Wi-Fi and Cellular Data activated my iPhone 5S will restrict ALL DATA to Wi-Fi or it will use shorts amounts of data from cellular?) for details of WiFi vs cellular data use.

why cant I enable Wi-Fi on my iPhone 6 but I can only use my celluar data

No one can answer such a general question. What happens when you turn on the WiFi switch on the phone?

Thank you for the reply- answered by thoughts perfectly! 😉

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