The acquisition is the latest in a string of purchases by SpiriTel, which sees itself as an active consolidator in the highly-competitive UC market and has bought 11 businesses since 2005.
It said today it hoped to start cross-selling mobile voice and data solutions into Nessco's customer base.
Nessco specialises in healthcare, local government and hospitality customers across Scotland.
It made sales of £3.2m and a pre-tax loss of £50,000 in the 12 months to 31 March 2009, but made a small pre-tax profit in the nine months to the end of December.
SpiriTel plans to integrate Nessco into its Business Division, which currently has offices in Cardiff, London and Wigan.
"[Its] operations are particularly complementary to SpiriTel's, and we are confident of a swift and effective integration," said SpiriTel chief executive Alastair Mills. "We are delighted to complete our first acquisition in Scotland, a deal of strategic importance to the group which will enable us to offer genuine nationwide engineering coverage to our growing base of customers."
Read more on Network Infrastructure Solutions and Services
IR35 tribunal sees Nationwide project manager lose £70,000 tax bill appeal to HMRC
General Election 2019: the Scottish National Party’s technology policies and digital plans
Chancellor Sajid Javid set to make £5bn investment commitment to improve UK broadband coverage
Boris Johnson has 12 months to reform broadband policy, says industry