EE has revealed all its customer service calls are now answered by staff based in the UK and Ireland.
According to the company, ensuring all calls are dealt with in the British Isles is part of its wider effort to deliver the best service in the telecoms industry.
Other improvements in recent months include upgrades to its My EE app, so customers have more flexibility and control over their account.
Furthermore, EE has launched its Network Status Checker tool so people can get real-time personalised updates on network performance.
Marc Allera, Chief Executive of EE, commented: "Customer service is a top priority for us, and 2016 was a landmark year in the service that we provided to our customers.
"We’ve delivered on the pledge we made last April to answer all EE customer service calls in the UK and Ireland."
Mr Allera also confirmed that EE is making strong progress towards its commitment to expand its superfast 4G coverage to 95 per cent of the UK by 2020.
"We’re passionate about making our service the best in the industry, so you can expect more to come soon," he added.
This comes after EE was identified by Ofcom as one of the most complained about providers during the third quarter of 2016.
According to figures from the regulator, the total volume of complaints it received about landline and broadband providers went up between Q2 and Q3 2016.
BT was the most complained about broadband provider during this period, with 36 complaints per 100,000 subscribers between July and September.
Plusnet was not far behind, with 30 complaints per 100,000 subscribers.
However, EE also performed poorly, racking up 26 complaints per 100,000 subscribers, compared with the industry average of 20 complaints for every 100,000 customers.