AT&T; hikes price of old unlimited data plans to $35/month - AT&T; customers who previously had unlimited data plans back in the iPhone 3G era and have managed to hang onto that plan are in for their first price increase in seven years.

The telecom operator will raise the price for subscribers grandfathered into unlimited data plans in the new year, adding a small increase of $5 per month.

AT&T; will apply the price increase to those unlimited plans sometime in February, meaning grandfathered users will see their total bill rise to $35 a month.

In 2007, AT&T; was the first company to offer the unlimited data for iPhone owners, but started capping data limits in June 2010.

In the switch to tiers, the operators allowed existing customers on unlimited plans to continue on those services indefinitely, except in the case when a subscriber drops out of a grandfathered plan they are not able to switch back.

AT&T; managed to hold off the price increase for over seven years, while its competitors such as Verizon, T-Mobile and Sprint have increased prices. Last month, T-Mobile and Verizon increased unlimited prices to $95 and $50 per month respectively.