Before buying a cellphone from another country you must first ensure it is compatible with your network provider. Some countries have closed down their 2G networks while 5G is still relatively new for most countries. As a rule the more frequencies support by your phone the more coverage you will have, especially when travelling between major areas.
Before buying a phone first check you to see which frequencies your provided uses. This can be done by checking by check on you providers website or copying the frequencies of a locally supplied phone. Alternatively if you can check using the GSM coverage table by country at WorldTimeZone. Ideally you should match all the frequencies used by your service provider. If you intend to travel overseas it would also pay to check these countries also to find the best phone for your overseas travels also.
Below some country specific links which can be used. We also recommend checking on your providers website.
Australia Frequencies
United Kingdom
United States and Canada
You may also need to convert the frequency code, for example B1 to the frequency or vise versa using the chart found in this link. B1 as an example is 2100MHz.
Once you know the frequencies supported by your provider simply match up using the chart below to find the sorted vivo smartphones.