BONUS: Mike Sievert mentions that T$-$Mobile's strategy involves making

substantial investments in customers. What does adding travel perks

amount to and is it a sustainable advantage?

It is a way to reduce supplier power and it is sustainable because

foreign networks do not have negotiating power against T$-$Mobile.

It is an increase in rivalry which is a cost for all competitors but its

sustainable because it cannot be copied.

It is an increase in rivalry which is a cost for all competitors but it's not

sustainable because all the main competitors he mentions can easily

offer the same.

It is a way to reduce the threat of new entrants and it is sustainable

because there are few potential new entrants in the market.