Waterloo Regional Police are asking the public to be careful when arranging sales through online sites.
Police say a man was robbed and received minor injuries after meeting with two men who arranged to sell a phone online.
The robbery happened on Doon Village Road around 10 p.m. on Tuesday.
Earlier in the evening, another man was assaulted after meeting to buy a phone, this time on Pioneer Drive.
The suspects in both cases are described as tall with dark skin, one with a slim build the other an average build, both wearing hoodies and sandals.
Anyone with information is asked to contact police or Crime Stoppers.