A year’s notice was more than enough for other internet service providers using the Digital Region network.
Sheffield-based Ask4 claims it migrated 500 customers to other networks with no downtime and just two issues.
Director Jonathan Thornhill says they sent the first letter in February and completed the process in July.
The firm specialises in internet in student accommodation and lost its domestic customers on Digital Region to other firms such as BT and Virgin.
The whole process from signing up with Digital Region - negotiating the contract, legal costs, R&D - to losing customers in the close down probably cost the firm about £350,000 he said.
But its reputation is intact.
He added: “We have congratulated the team. The situation could have been horrendous but it’s not caused us a problem.
“It’s a strange situation. We’ve lost customers but it’s gone incredibly well. Getting it wrong could have cost us thousands in the loss to our reputation.”