They are like PT.
PT has (the verb tense is going change to past soon) a huge monopoly on telephone and internet..exactly like you said they sold to other ISPs but as they were making very high prices it wasnt good for the other ISPs and they had to stop beause it wasnt giving profits to that ISPs.
Now the ISPs that were "ridicularized" by PT are making their own infrastructures and are competing with PT, example: Clix.pt they are making up to 8Mbits connection at 40 Euros which is very very cheap they are going to have 50% of the amount of lines PT has in the third trimester and someday 100% PT will start going down the pipe .
PT is losing a lot of customers because of the ISPs they tried to destroy in the past and because people are using more mobile phones than the wire phones.
And PT abuses of their monopoly by charging people who have their lines for 15€ month even if they dont make any calls so thats one more reason for changing to the other companies that are rising.