The Communication Workers Union (CWU) has shelved the industrial action ballot in BT due to "legal technicalities" that may have rendered the process null and void.
Unionised staff at the telco were last month asked to vote for or against striking over the offer of a 2% pay rise - CWU were holding out for 5% - and had until 5 July to return the slips.
CWU deputy general Andy Kerr did not specify the specific issues that forced it to cancel the ballot but argued "the law, in our view, appears to be outdated when it comes to the provision of information".
"The legal technicalities on which this ballot has been cancelled again raise questions over the right to strike and the extremely restrictive trade union laws that exist in the UK," said Kerr.
Members will be re-balloted "as soon as is practically possible" but CWU will also sit down with BT to re-evaluate whether the dispute can be resolved without a walk out.
He said the CWU had received several eltters from BT in recent weeks which amounted to a legal challenge and on receiving legal advice about the questions put to it by the telco, had decided to cancel the ballot.
BT said: "An amicable agreement is in everyone's interest and the withdrawal of the ballot provides both sides with a window of opportunity in which to reach such an agreement."