How to setup phones for phone automation

what I've figured out through reading multiple posts is that you need a 4g plan on a sim-card. and some say just buy 4g proxies.

and of course I might need to change device id.

i don't really know what is the best or what I should do.

Proxies are usually cheaper but if you have the upfront cost of multiple phones then you can save more money in the passing of time.

better buy 4g proxy, you can find cheap good solutions & save yourself some pain. better handle one thing & focus on it than 2 things imo