Despite criticism from journalists and industry analysts, the iPhone 4S saw a record-breaking amount of pre-order sales yesterday on AT&T.

AT&T has said that initial demand for the iPhone 4S has resulted in the most successful iPhone launch in the carrier’s history. The nation’s largest wireless carrier has reported 200,000 iPhone 4S pre-orders in the first 12 hours of availability.

CNET reports:

“AT&T has seen extraordinary demand for iPhone 4S with more than 200,000 preorders in the first 12 hours alone, the most successful iPhone launch we’ve ever had,” a company spokesperson said in a statement.”

Sites like AT&T’s wireless portal and Apple’s online store struggled to stay online after pre-orders opened around midnight PST on Friday. Many customers were unable to place orders initially due to the large amounts of traffic crippling the carrier’s servers. More pre-orders were able to be placed later Friday morning once the traffic bottleneck had been subdued.

It’s difficult to compare numbers with the iPhone 4 launch, because at the time AT&T was the sole iPhone partner. Apple added Verizon to the iPhone roster in February of 2011. Sprint was just added this last Tuesday.

According to Reuters, the iPhone 4 sold a record 1.7 million units in the first three days of availability. Day one pre-orders for the iPhone 4 reached 600,000 units on all carriers worldwide. 200,000 iPhone 4S first day sales on AT&T in the US bodes well for the 4S being Apple’s best-selling smartphone yet. Numbers for Sprint and Verizon have not been disclosed at this time, nor have international sales been reported.

Shipping estimates do indicate that there is very high consumer demand for the iPhone 4S.

International shipping estimates for iPhone 4S pre-order slipped to 1-2 weeks only hours after pre-orders opened up for customers around the world. Shipping estimates have also fluctuated in the US, with Apple now giving 1-2 week estimates for iPhone 4S orders across all three carrier partners.

The iPhone 4S will officially go on sale in stores next Friday, October 14. Expect there to be lines.