no internet after installation switching provider

Hello ans thank you in advance For your help.

I switched internet provider from Lombokxnet to T-Mobile.

Therefore, I changed the modem this morning but it seems I’m facing issues.

What I did:

1. Plug the modem to electricity. Start the modem. 
   i have indeed greens lights on

2. I connected my iPhone and iPad to the network. Login and password are correct. Unfortunately, I got the message “no internet connection”

I must have done something wrong or bad. My guess is that I did not setup the DSL cable? 
 

it seems that it is different from my previous internet provider where I just had to connect the cable.

But T-Mobile is asking me something different right? 
 

I can see this cable coming from the ground, is that one in need to plug for DSL ? Grey with colored wires.

last but not least, I don’t have DSL cable as mentioned in the documentation. Should it be included in the modem box or should I buy it myself?

Thank you for your infinite and grateful help.