Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 26, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Registrant Name	Zoom Telephonics, Inc.
Entity Central Index Key	0001467761
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Is Entity a Well-known Seasoned Issuer?	No
Is Entity a Voluntary Filer?	No
Is Entity's Reporting Status Current?	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Public Float			$ 32,538,240
Entity Common Stock, Shares Outstanding		35,362,854
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Interactive Data Current	Yes
Entity Incorporation State Country Code	DE
Entity File Number	04-2621506