The Manx government said the 111 team is dealing with a surge in calls.
The increased workload is largely due to an influx of calls from people reporting results from free home testing kits.
Last week the health department announced a change in quarantine rules for close contacts of those who have tested positive.
They are now able to use lateral flow tests.
If you're phoning in with or for results, you may struggle to get through first time, added the government.
The advice is to hang up and try later rather than wait on the line or make repeated calls.
Anyone with a positive result or symptoms is required to self-isolate.
Meanwhile the Manx police said officers are patrolling the Grandstand COVID-19 testing area following reports of NHS staff being verbally abused by people waiting for their tests.
Health Minister David Ashford said: "I understand that this is a frustrating situation for many people, and would ask for your understanding at this time of high demand. Our 111 team is very busy at present.
"If you can’t get through when you call, there is no need to worry – the important thing if your LFD test is positive or you have symptoms of coronavirus, is to stay home and prevent the spread of the virus. The team will get to you, but it may take a day or so in the current circumstances".