BT Group has unveiled its plan to invest £6 billion (nearly $8.7 billion) in faster broadband and improved mobile services over the course of the next three years.

The holding company aims to bring "ultrafast" broadband connectivity to at least 10 million home and enterprise customers by 2020 and, if all goes smoothly, the number should reach 12 million. Included in the carrier's list is boosting the coverage of 4G mobile services.

The majority of clients will benefit from the upgrades through BT's G.fast program. At the moment, G.fast offers speeds of only 300 Mbps, but after the investment plan rolls out, the speed should spike to 500 Mbps.

Regulator Ofcom estimated that households in the United Kingdom had an average speed of 29 Mbps in 2015. The increase in speed should provide household customers with plenty of bandwidth for streaming movies and online gaming.

BT's leader, Gavin Patterson, says that customers will get "affordable as well as fast" broadband by means of G.fast and, to a lesser extent, FTTP.

On the mobile front, BT wants its phone network, EE, to reach 95 percent 4G coverage until 2020. Currently, EE covers only 60 percent of the country with its 4G footprint.

Multiple sources from the UK broadband industry point fingers at BT and chastise it for postponing the investments. Some have suggested that BT's subsidiary Openreach, which controls UK's last mile copper infrastructure, should split from the holding and operate on its own to increase the competitiveness of its services. Ofcom decided that the two companies should remain under the same roof.

Openreach announced that it plans to create 1,000 new engineer openings in 2016, so there is extra flexibility in the work they can do for customers.

The UK is one of the world leaders when it comes to broadband coverage. About 90 percent of the country can tap into ultrafast broadband connections on fixed networks, and the number should rise to 95 percent by 2017.

Not everyone is enthusiastic about BT's expansion plans, however.

Sky, one of BT's rivals, points out that G.fast technology utilizes copper wires, and mentions that BT should build a future-proof fiber network.

"Despite BT's claims, it is clearer than ever that their plans for fiber to the premise (FTTP) broadband will bypass almost every existing UK home," notes Andrew Griffith, chief financial officer of Sky.