Investors hoping Apple Inc. will smash all smartphone sales records with its soon-to-be-released iPhone may need to take a step back and consider what Maynard Um of Wells Fargo has to say.Um highlighted a headline from AT&T Inc. in which the telecom giant said it is expecting upgrade rates from consumers to be permanently lower than historical norms.AT&T noted that its equipment revenue fell $0.5 billion in its recent quarter and this was attributed to a record-low upgrade rate in which it sold one million fewer phones than the same quarter a year ago. When the company was asked if this represents a permanent or cyclical trend, the company said it believes this trend is here to stay.Smartphone owners looking to buy a new phone aren't as compelled to do so today; software upgrades are sufficient — especially at a time when consumers are spending less.Source