ISME has said it fears that Eir's withdrawal from the tendering process of the National Broadband Plan will delay the scheme to 2023.
The association is concerned that the plan will deliver only at a greater and unknown cost, and the delay will greatly impact businesses and homes throughout the country.
They said Eir's withdrawal is the "latest in a string of failures", and they have "serious reservations" about the way the Department of Communication, Climate Action & Environment is running the current tendering process.
ISME CEO Neil McDonnell called for a review, saying: "Yesterday's announcement is a blow to the roll-out of the National Broadband Plan and raises many questions about the manner in which the Department of Communication (DCCAE) is running the process.
"Eir's withdrawal will bring unanticipated costs, unacceptable delays and as things stand, makes the bidding process a one-horse-race."
"Our most recent research on broadband services among our members shows that 29% have inadequate broadband services. Yesterday's announcement will prolong this poor level of service. This is unacceptable."
ISME Council Member, Ross McCarthy of Keystone Procurement, said: "SMEs are the backbone of the rural economy and cannot compete without a modern communications network."
"From a procurement perspective, ISME has had reservations since the State gave Eir low hanging fruit to connect to high speed broadband. While this may have been done to speed up roll out, the risk was always that others in the process would be left with more difficult, costly connections to deliver"
Mr McCarthy has called for the Government to prioritise broadband provision for the main towns in each county that do not already have high-speed coverage.
Eir is blaming the Government for its decision to withdraw its contract bid.
CEO, Richard Moat, says the process was too complicated and the Government was paying too little.
He said: "We anticipated that we would be able to charge those prices which had been set by the regulator.
“There was an indication by the department that they would be looking for discounts, potentially significant discounts on those prices.”