 Internet usage has increased rapidly since 2000 — the number of users grew from 430 @,@ 000 to 3 @.@ 4 million ( 48 per cent penetration rate ) in 2010 . Telephone services are widely available , and a central digital trunk line connects most regions . More than 90 per cent of fixed lines are served by the Bulgarian Telecommunications Company ( BTC ) , while mobile services are provided by three operators — <unk> , <unk> and BTC / <unk> . 
