Just this afternoon I noticed a message on my dumbphone telling me I'd used up 10Baht then 34 Baht for 'today's internet usage. I have a TOT wireless package for years now and pay when then the bill for 630B comes in every month. They charging extra for external device usage now?

You're using your TOT wifi package when there's an antenna within reach and you connect to their signal.

If you're not connected to any wifi and you have data (3G or maybe GPRS/EDGE) active on your phone, it will revert to this service for data connection and AIS will charge you for this. That's what has happened here.

Make sure that 3G/GPRS/EDGE data are disabled on your phone.

By the way, you mention "dumbphone" which I find confusing. What kind of "dumbphone" has wifi? or was that just a play of words?

^ +1

I have the same setup as the Op, ToT WiNet and I never (when around the house) enable data on my phone to avoid unnecessary charges and thus only use the ToT Internet.

Only when going out (and when needed) I enable the Data on my phone.

Even old dumbphone will connect to the internet if mobile data not turned off.

About one thread per week.

Agreed, what suprised me was dumbphone with wifi capability.

You're using your TOT wifi package when there's an antenna within reach and you connect to their signal.

If you're not connected to any wifi and you have data (3G or maybe GPRS/EDGE) active on your phone, it will revert to this service for data connection and AIS will charge you for this. That's what has happened here.

Make sure that 3G/GPRS/EDGE data are disabled on your phone.

By the way, you mention "dumbphone" which I find confusing. What kind of "dumbphone" has wifi? or was that just a play of words?

Thanks. I'd been buggering about with my 'smartphone', Samsung Galaxy j7, and had inadvertently switched the 'mobile' tab on.

To be sure from further accidents, you can also switch off mobile data at AIS, so that even changing the mobile data setting on the phone will do nothing.

From this thread of @Richcor:

http://www.thaivisa.com/forum/topic/870588-ais-credit-vanishing/#entry10077125

Copy/paste:

AIS / One2Call: Manually Activate-Deactivate Data Service

Some apps on phones, smartphones, or tablets may have auto-data
connections feature. To prevent unintentional use, the user should
deactivate the data service when not in use.

Works for both Post- and Pre-Pay AIS accounts

To deactivate data service Dial * 129 * 1 # call

To activate data service Dial * 129 * 2 # call

To check data activation status Dial * 129 # call

Useful extra tip from KhunBENQ above.

Glad you've figured it out. Don't be too hard on your J7. Granted it's kind of low-end in the Samsung product range, but it's still quite a decent phone IMHO. Don't think it's that "dumb"

Useful extra tip from KhunBENQ above.

I think @Richcor has brought it first.

Praise goes to him.