BT, TalkTalk and Virgin have signed up to a broadband code of practice for small businesses as Ofcom released new research Thursday. The media regulator's research found about 20% of small businesses were unhappy with not being able to access the internet speeds they were led to expect.The three internet providers named above said they would be covered by a code similar to consumer protection rules. The code is due out in autumn.Meanwhile, Ofcom said its analysis also revealed about 18% of small to medium enterprises might not have superfast broadband by 2017 when 95% of premises are expected to have access."This is partly because it usually costs more to connect business premises than households, and because current deployment plans are designed to maximise coverage among as many premises as possible," Ofcom said in a release.The regulator recommended the government set explicit targets for business coverage.