So, you can't set it up online but if the reason you are asking is because you do not have access to your phone to do it the traditional way​, you can always Contact Us and we can set it up for you.

Great, thank you so much,

C

I need to do this as well so I contacted customer service and they said they will not do it and I have to buy a phone.

Oh no! I am sorry @queencari this is something we can definitely do over the phone for you and I think there might have been some confusion on our part when you called. If you have a moment, please do call us again or if you have a Facebook or Twitter account, you can use the links in my signature to message our T-Force folks who can also do this for you.

The traditional way​, link is broken. How do I setup call forwarding?

Tdogg reported two years ago and still no link to how to set up call forwarding. All links are broken or missing.ill have to call them. 

Can I turn call forwarding on and then turn it off

Can I easily end the call forwarding at any time?

Apparently they won’t do it for you anymore. My dads phone died and I’m trying have his calls forwarded to my Moms phone. Support won’t do it and says you have to do it from the device.  After being on chat with them for 30 minutes, telling them the device was dead, and them sending me the instructions on how to do it on the device… I have NEVER had a good experience with T Mobile support.. Utterly useless