A GP partnership received more than 600 calls from patients in the space of just one hour this week, in a stark sign of the demand facing the region's practices.
Humbleyard Practices, which runs GP surgeries in Cringleford, Hethersett and Mulbarton, said it received 669 calls from when it opened on Monday morning at 8.30am until 9.30am, a rate of one call every five seconds.
Health experts say other surgeries across the region are facing similar levels of demand, as all areas of the NHS come under huge strain.
The situation has prompted frustration among many patients and led to health bosses warning of a "sustained increase" in GPs and staff receiving abuse.
The south Norfolk-based partnership said it has even had to resort to reporting cases of online trolling to the police.
In a post on its Facebook site, a spokesman wrote: "We are oversubscribed by almost 5,000 patients.
"We try to answer calls as quickly as possible, but this number clearly indicates why patients are being held in a queue or being asked to call back because the lines are busy."
While Humbleyard attributes part of its strain to a growing number of housing developments nearby, demand facing primary care continues to be an issue across the county.
In August alone, 556,365 appointments were held in Norfolk and Waveney - although these include telephone appointments and ones not with a doctor.
Just over a quarter of these -26pc - followed a wait of longer than two weeks.
Of these appointments, 206,323 were with GP doctors, with the vast majority - 87pc - being seen in less than two weeks.
At the beginning of her tenure as health secretary, Therese Coffey set out this two-week period as a key target for GPs.
Sadie Parker, primary care director at NHS Norfolk and Waveny, said: "GP practices across Norfolk and Waveney are incredibly busy.
"We understand that it may be frustrating to wait for some time on the phone, but we urge people to be kind and patient to GP practice staff; they have and continue to work incredibly hard to provide the care you need.
"NHS Norfolk and Waveney has zero tolerance for abuse or violence directed at health and care staff.
"They should never be subjected to verbal or physical abuse for doing their job and abuse, aggression or violence will not be tolerated."
Healthwatch reaction
John Bultitude, head of communications at Healthwatch Norfolk, said: "We are concerned at a reported rise in abuse to GP practice staff.
"There is no excuse for personal attacks, threats of violence or worse, and incidents like this do need to be investigated and perpetrators dealt with.
"Organisations across health and social care, including the Norfolk and Waveney integrated care system and ourselves, want to make it clear there are a range of different staff in a practice who can help you, including nurse practitioners, mental health practitioners and physiotherapists.
"We acknowledge there is still a lot of work to do around communicating this.
"While this will not ease the phone queues, which is a capacity and technology issue, getting the right help for a person can speed up getting the treatment and help they need.
"Meanwhile, we are in regular contact with the Humbleyard practice to understand their issues.""
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