BT claims that it is doing its best to protect services after The Communication Workers Union (CWU) escalated its strikes to emergency call workers.
BT gave its employees a £1,500 pay increase earlier this year but the CWU said that was a pay cut when taking into account inflation.
Some 40,000 telecoms engineers and call-centre staff are now being joined by critical-service workers to go on strike over pay in October.
The CWU has now served notice on BT for four days of strike action on 6, 10, 20, and 24 October.
A spokesperson for BT said: “We will do whatever it takes to protect 999 services – redeploying our people to the most important priority is a normal part of BT Group operations.
“We made the best pay award we could in April and we have held discussions with the CWU to find a way forward from here. In the meantime, we will continue to work to minimise any disruption and keep our customers and the country connected”.
