The South Western Ambulance Service has issued a warning saying it must prioritise critically ill patients as it continues to experience very high demand.
The ambulance service recently had its busiest week on record, responding to more than 22,000 incidents during a seven day period.
It has experienced a significant increase in demand following the easing of lockdown restrictions.
The South Western Ambulance Service NHS Foundation Trust (SWASFT) has dealt with more than 20,000 incidents per week since the start of May, compared to around 18,500 incidents per week in early April.
SWASFT is reminding people only to call 999 if someone is seriously injured or ill and their life may be at risk.
It is also asking them not to call back for an estimated arrival time to ensure others can get through to its emergency control room.
A spokesperson for the ambulance service said: “Our service is currently experiencing very high demand, which means we must prioritise critically ill patients.
“We are asking the public only to call 999 in a genuine medical emergency when somebody is seriously injured or ill and their life is at risk, and for other medical concerns we encourage patients to contact NHS 111 for advice and support.
“Please do not call us back to ask for an estimated arrival time, and only call back if the patient’s condition worsens or you no longer need our help.”