EE has admitted that thein the UK has gotten off to a bumpy start, with some customers receiving no service for up to 24 hours.
The operator, which also runs, became the first to introduce 4G services in the country when its network went live to the public on 30 October. However, on Saturday, ZDNet received reports that some customers migrating from the Orange network to EE's 4G network were having problems. They complained they had no service at all, leaving them unable to send or get texts, or take incoming calls.
On Tuesday, EE conceded that the launch has seen a few teething problems for some users.
"The launch of our new brandhas been, on the whole, a great success," an EE spokeswoman said. "Unfortunately, we've also seen a few issues emerge, mainly around our systems and training processes, that have affected a small number of customers trying to migrate to EE from Orange or T-Mobile."
Other EE subscribers took to Twitter to air their displeasure at the network's bumpy start, which included a lack of communication with customers.
If technical mishaps and training issues weren't enough, some customers also received the wrong SIM cards for their devices, again leaving the handsets unable to be used as intended.
One wannabe 4G early adopter, social media expert Andrew Grill, complained on his blog of receiving the wrong SIM card on more than one occasion.
His problems were compounded when he received conflicting messages to contact Orange and T-Mobile customer service staff, even though he visited EE stores on three occasions in an attempt to sort out the situation.
EE said on Tuesday that Grill's situation has now been resolved, as have those of other customers experiencing problems.
"We've also identified some SIM distribution issues from last week, which saw the wrong SIM being picked from our warehouse, adding a delay for some customers accessing the EE network," the company's spokeswoman said.
"We're disappointed that we've experienced these teething problems, and apologise for any inconvenience caused, but are confident that we've now resolved these issues."
Since launching the service, the company has received criticism for its, primarily for the data limits imposed and the lack of an unlimited option.