Royal College of Nursing (RCN) Staff at both Shropshire Community Health Trust (Shropcom) and the Robert Jones and Agnes Hunt Orthopaedic Hospitals (RJAH) voted in favour of strike action earlier this month.
The RCN has said that what will be its first national strike will take place on December 15 and 20.
Details will be set out soon about which services within the NHS will be exempt from the action.
Services deemed "life-preserving" and "emergency-type care" will continue on strike days, a nursing chief said, but she declined to give exact detail about which departments would remain staffed when colleagues stage a walk-out.
In similar statements both Shropcom and RJAH said they were working on plans to cope with the action.
Stacey Keegan, chief executive at The Robert Jones and Agnes Hunt Orthopaedic Hospital, said: “We are in the process of working on our business continuity plans, ensuring we maintain patient safety, and will contact anybody who will be directly impacted in due course.”
Echoing Ms Keegan's comments, a spokesman for Shropcom said: "We are in the process of working on our business continuity plans to ensure patient safety is maintained. Anybody who will be impacted will be contacted in due course."
RCN general secretary Pat Cullen has meanwhile urged Health Secretary Steve Barclay to "stop the spin and start to speak" with nurses to avert a walkout, accusing him of having "chosen strikes over speaking to me".
Mr Barclay has said the nursing union's demands – which he cited as a 19.2 per cent pay rise, costing £10 billion a year – are "not affordable".
But Ms Cullen said she does not recognise the Health Secretary's figures and said she had made it clear she wished to discuss "non-monetary issues" in any talks.
Both Mr Barclay and Ms Cullen insisted that their doors are open for talks.
Prime Minister Rishi Sunak said he has "enormous respect" for nurses but that the pay rise requested by the union is "obviously unaffordable".
He said: "What the unions are asking for, I think, is a 19 per cent pay rise.
"And I think most people watching will recognise that that's obviously unaffordable, and that's why I'm pleased that the Health Secretary is sitting down, talking to the union, and hopefully we can find a way through this."
Ms Cullen said there will be "very detailed and worked-through plans" set out soon about which services will be staffed, with a local strike committee in each organisation that has voted to take industrial action in England, Wales and Northern Ireland.
She said the committees will include clinical experts who will "guide and direct all decisions that will be made".