How to use an iPhone 4 without data/ activate it?

I have an iPhone4 6.1.3 that i got for $1 with one of my moms 2 year contract upgrades(att). And I'm going to try to use it without data (I all ready have a phone with a sim card).

But will I get charged full price for the iPhone if I don't activate it within a time period?

I have been using it as an iPod for a couple weeks. I don't know if that initial activation when I turned it on and set it up works(it came with a sim card in it but there's no service), or if I need to activate it with my moms sim card.

If so what do I need to do to use her sim card to activate my phone and then return her sim card to her phone?

Also any tips on using an iPhone without data?
P.S. I'm fine with jailbreaking.

To use this service do the following:

Put the AT&T Sim card in the already activated iPhone.

Make a Wi-Fi connection to a local Wi-Fi source.

Navigate to this page. Click "Continue To The Next Page".

Click Disable Data (Fake APN). The Install Profile window appears.

Click Install. Another Install Profile window will popup warning you that authenticity of this profile can't be verified. Click Install on this window too.

You should now see a message stating "Could not activate Cellular Data Network; You are not subscribed to a cellular data service.

You should now be able to make phone calls and be able to use Wi-Fi to access the internet. When you aren't connected, you should get an error.

To remove the 3G/Edge block, simply go to your Network settings and removed the Fake APN profile.