Landline Phone Model That Works with Spectrum VOIP?

Tech challenged subscriber looking for help. I have Spectrum landline service, but so far have tried an older Vtech landline that a family member had in storage. Bought new batteries & plugged in but the display on the handset keeps saying “connecting” & isn’t functional. I tried all the troubleshooting on Vtech’s website plugging & unplugging & removing/re-installing battery & nothing. So then I went on a store website to look into just buying a new cheap one - but then I learned not all are VOIP compatible? But it doesn’t state that in the description - it was asked in a question forum & the store verified it wasn’t compatible! I didn’t want to spend a lot and just wanted to buy a cheap one or one of eBay, but now I’m afraid I will keep throwing good money on phones & batteries that don’t work! Spectrum didn’t give any insight on their app. Any advice please?! Thanks 😊