By Josh Ong

Published: 09:20 PM EST (06:20 PM PST)

AT&T issued a statement Wednesday refuting T-Mobile's claim to "America's largest 4G network." The Skyfire browser iOS app, which converts Flash video to HTML5, "sold-out" after just 5 hours of availability, and a security flaw in the PayPal iPhone app could let hackers intercept user passwords.

AT&T vs. T-Mobile

AT&T responded Wednesday to T-Mobile's claims that it has "America's largest 4G network," asserting that AT&T has better deployment than T-Mobile on the High Speed Packet Access (HSPA+) technology, which T-Mobile has labeled as 4G.

T-Mobile fired the first shot this week with a new advertisement that parodies Apple's award-winning "Get a Mac ads. The ad features a woman as a myTouch 4G and a man as an iPhone 4 who is slowed down by the "old AT&T network." The commercial goes on to say that T-Mobile has "America's largest 4G network."

In Wednesday's official statement, AT&T presented figures that it believes counter T-Mobile's assertion. "T-Mobile's claims about 4G are based on the same HSPA+ technology we have deployed to 180M people today, more than T-Mobile's reported 140M, and we'll have it rolled out to 250M people by the end of this month, substantially more than the 200M T-Mobile says it will have by year end," read the statement.

Also at issue is whether HSPA+ is actually a 4G technology, as it is often called 3.5G. HSPA+ is seen as a stepping stone to the faster Long Term Evolution (LTE) technology.

Skyfire

According to an official blog post, demand for the new Skyfire for iPhone app overloaded the company's servers, causing the app to 'sell out' in just 5 hours.

"The user experience was performing well for the first few hours, but as the surge continued, the peak load on our servers and bandwidth caused the video experience to degrade. Thus we are effectively ‘sold out’ and will temporarily not accept new purchases from the App Store. We are working really hard to increase capacity and will be accepting new purchases from the App Store as soon as we can support it," read the post.

The new browser app for iOS had appeared on the App Store for a few hours Wednesday before being mysteriously pulled. The app offers a remote Flash to HTML5 conversion service that allows iOS users to watch Flash video content on the web, although popular TV streaming site Hulu won't work with Skyfire.

PayPal

According to The Wall Street Journal, PayPal rushed out an update to its iPhone app after being alerted to a major security flaw that could allow hackers to gain access to users' accounts. The PayPal app was updated Wednesday to version 3.0.1, which includes "an important security update."

Because an earlier version of the app neglects to confirm the authenticity of PayPal's website, a hacker can redirect an unsuspecting user to a fraudulent version of PayPal, although the attacker would need to be in the same physical location or on the same Wi-Fi network as the user.

Andrew Hoog, chief investigative officer at viaForensics, the security firm that found the flaw, called it a "colossal oversight" by PayPal.

A spokeswoman for PayPal told the Journal that she was not aware of anyone having been affected by the vulnerability yet, and promised that PayPal would reimburse any fraudulent activity resulting from the flaw.

As iOS apps deal with increasingly sensitive financial and private information, security experts have cautioned users to be more careful. Early in October, a security review found that 68 percent of the top iPhone apps in the App Store transmitted an unencrypted unique device identifier that could reveal personal information.