The government will not "bail-out" a listed company. Eskom, SABC and SAA are not public companies, they are sole owned by the government.
Telkom doesnt not need a bail-out, but if the situation arose that they started to lose money, they would have to raise cash through the same means as other public companies (issues shares, loans etc) or it would be bought out by some company that wants the infrastructure or which thinks it could turn Telkom profitable.
If the government bailed them out, the ordinary shareholders would gain at the governments expense.
The government owns massive shares in other public companies (like PPC, MTN, SASOL, Vodacom etc) through the PIC and it wouldnt bail them out either.