One of the company's 60,000 customers has made the 500 millionth call routed by the company since it launched, and at around about the same time Unicom also completed 1 billion minutes of call time sold.
Unicom, based in Manchester, has regional headquarters in Birmingham, Ipswich, Leeds, Milton Keynes, Newcastle-upon-Tyne, Nottingham, Sheffield and Stoke-on-Trent.
"We add around 20 million calls and something like 40 million minutes of talk time every month," said Chris Earle, Operations Director of Unicom.
Unicom credits its growth and success to a call centre with a difference - a 'normal' phone number, and UK-based people answering incoming calls in around six seconds.
"We're a relatively small business with a small, closely-knit and efficient management team - and we are absolutely clear in our minds about what makes the difference to our customers: a UK call centre with real people answering the telephone, 98% of calls answered within six seconds, and managers and directors who are hands-on and accessible," said Chris Earle.
"Our customer retention level is currently running at 86% against a sector average of around 70%. Of the 14% we lose, only a third go to competitors, the remainder being businesses that close or move premises for one reason or another, which is obviously beyond our control."
Unicom's 60,000 customers are primarily small or owner-managed businesses with telephone bills of approximately £1,000 a year. The specialised nature of the telephony and broadband products offered by Unicom provides significant savings for its business users.
"We've not actually had a price increase since we started offering our telecom services in 2001," said Chris Earle.
"We use BT's infrastructure and network, so beyond the occasional glitches any provider can expect, our service is as robust as they come."