A mobile phone network used by a first responder medical scheme has been out of action for "two weeks".
Hugh MacPherson, of Acharacle Community Council, said the loss of service since 9 January was "unacceptable".
Network provider EE said it was aware of signal issues affecting the Acharacle area in Lochaber and has apologised to customers.
First responders provide out-of-hours emergency medial care in remote parts of the north west Highlands.
They include nurses, retained firefighters and volunteers.
Mr MacPherson told BBC Radio Scotland a lot of hard work had gone into setting up Acharacle's first responder scheme, and selecting a phone network.
He said the Orange EE network had offered the most reliable way of communication.
The network had been expected to be working again on 14 January, but that date has been pushed back to 23 January.
Mr MacPherson said: "Two weeks without the network is quite unacceptable.
"Various reasons for the cause of the fault have been given, and conflicting timescales for when the service will be back."
He said the situation was also a concern for carers and vulnerable people they looked after, adding: "Not everyone here has a BT landline and only have a mobile phone."
A spokesperson for EE said: "We are aware some customers have reported signal issues in the Acharacle area and we're investigating as a matter of priority.
"We apologise for any inconvenience caused whilst we work to resolve the issue as soon as possible."