Every time I buy something online, or make an account for an example month bus ticket, they "need" my phone number. I always use alias emails, but I don't have an alias phone number. I know, there are some online phone nr service, but they mostly dosnt work, outside of the US. So I was thinking about getting me a second nr, just for thoese cases were I have to log in. I would by the nr, in cash, and there is nothing data they have to make the nr. But what are your thoughts? What do you see as pros and cons for getting a second nr.? Does it even make sense, when the simcard is in the same phone?
Depends on your local laws and such, but in most European countries you can get a prepaid SIM card for a couple of euros/pounds/whatever at any supermarket, making them practically free. If you need a temporary number for a scammy special offer or any situation where your number is publicly visible (Gumtree, etc) it's a no-brainer IMHO.
If your phone suppprts running two SIMs at once, it has two IMEIs so as far as the network(s) are concerned it's two distinct handsets unless they deduce otherwise.
A fun aside: years ago I did some work for a small phone company (the company was small, not the phone) and they gave me a SIM with 100 numbers in a block and access to a portal I could manage them with. Sadly, I forgot to pay the annual £10 renewal fee.