T-Mobile and Walmart announced on Tuesday that the Walmart Family Mobile plan now offers unlimited talk, text and web for $45 per month. Additional lines cost just $35 per month. Until Tuesday, Walmart’s plan did not offer unlimited web access, but there’s a big catch: the unlimited data doesn’t always provide 3G data speeds. Instead, those who sign up before March 16th will be able to consume up to 5GB of data at 3G speeds. After March 31st, however, new customers will only be able to surf at 3G speeds for the first 250MB. Customers interested in purchasing the plan can do so in any nationwide Walmart store or by visiting Walmart.com. T-Mobile and Walmart said the decision to add unlimited data was because 44% of first-time smartphone buyers so far this year have said the high cost of data has been No.1 reason they delayed buying a smartphone.