Q: Can I use my Apple cellphone service with my wifi iPad?

Don't know if T-Mobile supports a hotspot or not. I have AT&T and it does. In my case I am able to use my iPhone as a hotspot for my iPad. I suggest asking T-Mobile.

They'll work fine together. A iPhone has both wifi and cellular capabilities

You can use you iPhone as a hotspot for your iPad when you aren't near a wifi network.

Used together you can get phone calls on your iPad if the iPad and iPhone are on the same wifi network. See article below.

You can sync info using iCloud.

Use Continuity to connect your iPhone, iPad, iPod touch, and Mac - Apple Support

Edit. Rereading your title it says cell phone service.  Now you know additional ways they'll work together.

Thanks, I hadn't thought of carrier availability. It appears they have a hotspot available.

https://support.t-mobile.com/docs/DOC-15778

From your link it looks like the OP should be able to use it.... 

I need to learn to read. Burgess asked for cellular service so I gave him all ways the two devices could be ysed together. 

bobseufert wrote:

 

I gave him all ways the two devices could be used together. 

Nothing wrong with that....

AT&T recently announced an enhanced service. If you have multiple Apple devices, including at least one iPhone, you can use any of your devices (iPads, iPod touches, other iphones, Macs) with any WiFi connection for phone calls through Facetime using your iPhone's number. It does not have to be the same WiFi network, and the phone doesn't even have to be on. Further, if you are traveling outside the US, calls to US numbers via this service are free.

The feature is called Number Sync, and the details are here: https://www.att.com/esupport/article.html#!/wireless/KM1062362

You're welcome. Since you said you're new to Apple allow me to give you the links to both the iPad and iPhone User Guides. They're not the most exciting reads but all the info is there. And if you can't find something please don't be a stranger.

iPad User Guide for iOS 9.3 by Apple Inc.

https://itun.es/us/U4OT9.l

iPhone User Guide for iOS 9.3 by Apple Inc.

https://itun.es/us/gVOT9.l

You're welcome.