I don't know if there are several ways, but I am aware of what is called spoofing, where you use a service or perhaps an app, and you follow their spoofing instructions to make it appear their number is sending texts or making their call.
Years ago, when I'd initially heard about spoofing and wanted to see how it worked, I found a website, created an account, followed their instructions and spoofed my spouse.
The website had a disclaimer stating they keep all information that you do but didn't use it against you unless you did anything illegal and the law became involved, that they would disclose your records.
Spoofing worked (at least back then - and I am talking 10 years back so trying hard to recall the steps) ... spoofing worked by placing a call to the very number that you intended to use to spoof someone with. I cannot recall how, but that person never received information of your phone call, so never knew it was you calling.
The key is that the call you placed to said number must be answered by said said number., and somehow that made spoofing work to be able for them to make it appear you are doing the sending/calling to another number.
What I am unsure of is if a call goes to voicemail, if that also can complete the spoofing attempt.
I am not certain if anything about spoofing has changed in all this time, but I can verify that it worked for me.
I do not have records of the website, which supposedly was legal, and I never used it a second time. I was purely curious to see if spoofing was a real thing. It most certainly was.
Someone else may be more helpful and more knowledgeable, but this the one way that I can attest worked.
A friend called to tell me he'd gotten a text that was apparently from me (from my cell #) but it was a scam. I know I didn't send him that text.
Question is, how did someone associate his phone # with mine.
(A) Hacking one of our cell phone providers' records?
(B) An app we both use that has access to our phone numbers and records on our phones?
(C) Something else....... ???
...and how does he, or how do I, keep this from happening in the future?? Thank you.
--Submitted by R. A.