I don't get text msgs when my data is turned off...i didn't know you had to have this on...and this never happened before...it just started happening after I got the 950XL
I had a Lumia 920 and Lumia 520 before...and I'm confused because I didn't have a data plan but could still send text msgs...i also read on other forums Thar you don't need data for sms, for mms yes, but not for sms
Cellular data of a form is needed to send/receive, but it doesn't count toward data use in most cases. In "Ye Olde Times" it was often charged by message, now it is mostly free.
Maybe I over simplified.
SMS should be using cellular signal. It was part of the GSM network (2G) originally. It's your most basic connection to your carrier. But the protocols have evolved, now SMS exists in many forms across GSM, CDMA and even 3G.
Much of this is going to depend on how your carrier is implementing their Short Message Service Center. Perhaps your carrier is using 3G to carry SMS traffic?