Ah, ok… I used to use usmobile.com as a data backup on their cheapest plan. It was ~$8 USD for 2Gb of data and like 100 texts per month. Obv a lot more than voip.ms, but you get assigned a real number by a cell provider. U.S. based though so it might not be useful for you.
If it matters, I believe “voip.ms” is Canada based. I’m using them for a phone number with sms, kind of like what you said you’re looking for.
IIRC, I’m paying ~$12 USD per year (+ $1 USD per month for a phone voip app, but there are free app options too).
YSK, their site/service setting aren’t always the easiest to figure out so read their docs carefully.
Best of luck!
Because you mentioned Islanders, maybe Dorfromantik?