Cerillion warned that its full-year results would fall short of market expectations, as delayed customer orders held back the billing software company.
The company now expects revenue of £46m to £48m for the year to 30 September, below the £52.8m analysts had forecast, with adjusted EBITDA margin at 43% to 45%, down from 50.9% a year earlier.
Cerillion shares were down more than 20% at the open on Monday.
Although the second half will be significantly stronger than the first, as it had flagged at its interim results, the company said the year would now come in behind consensus.
Cerillion blamed the shortfall on delays or deferrals in some new and existing customer orders, including software licence expansions and upgrades.
It said its major implementation projects were progressing, with work nearing completion at UCom and software installation finished at Omantel, and that its back-order book and new customer pipeline remained strong.