A teachers’ union leader has added her voice to growing calls for an investigation into how schools were allowed to sign up for “free” mobile phone deals which have left them £700,000 out of pocket.

Insolvency experts RSM Tenon were appointed to wind up ETC Communications Limited trading under the name Link Telecom.

The company struck mobile phone ‘cash back’ deals with schools across Bradford district to provide 9,000 connections to the O2 network.

Cashback money, made up of commission from O2 paid to Link, dried up when Link Telecom began suffering financial problems.

A total of £500,000 is owed to schools in the Bradford district, with another £200,000 to others in the wider West Yorkshire area.

Pam Milner, deputy secretary of the Bradford branch of the NASUWT union, said: “Where does this leave the users who were benefiting from these phones?

“Schools have lost out, teachers are disadvantaged and we need to restore the balance.

“I would call for an inquiry into this. It is a huge amount of money that schools cannot afford to pay.”

Link Telecom’s managing director Gary Fawcett said his company’s financial difficulties started when O2 changed the terms of its agreement about the amount of commission it was paying for the three-year schools’ deals.

Many of ETC’s creditors fear they may not get their money back after Alexander Kinninmonth and Duncan Robert Beat, of RSM Tenon Recovery, were appointed as Joint Liquidators today.

A spokesman for RSM Tenon Recovery said creditors would be paid “in order of priority” when ETC is wound up.

RSM Tenon said in a statement: “Agents were instructed to value the company’s assets, excluding debtors, prior to the meeting of creditors with a view to achieving a sale of the same following the Joint Liquidators appointment.

“A number of expressions of interest have been received in this regard and our agent will deal with these shortly with a view to achieving a sale at the earliest opportunity.”

When asked by the T&A what the prospect was of the schools getting money back, RSM Tenon said it was unable to comment until the assets are released.

Bosses at Link Telecom are looking to sell off its former holding company Link Telecom Holdings and subsidiary Voice Connections Limited, which are both in administration.