If Apple (and IBM) had been banned from communicating through long distance lines, except with ATT's permission, then it's hard to see how Western Electric (aka ATT) wouldn't have taxed all the nascent PC companies and retained enough profits to remain larger.
Edit: And on the later, iPhone side, that was the luck of power dynamics (single strong device manufacturer, bargaining against multiple competing cellular providers) coupled with phone company executive shortsightedness. If the cell phone industry has been less diverse (e.g. original ATT above), nobody would have felt the need to grant Apple any concessions.
The deal was done with Cingular ( Later acquired and merged with AT&T ). Neither AT&T and Verizon wants to deal with Apple at the time.