Yes and no. No, you can't buy a VoIP number and use it as your contact immediately and indefinitely. You would be amazed at how few companies update their list of VoIP vs POTS/Carrier numbers though. Hypothetically, one could transfer their carrier number to a VoIP provider, and use it for damn near everything. There would be trade-offs [0], of course, but I can attest to its effectiveness as a workaround.

[0] Trade-offs include a glitchy MMS experience, easy, automatic, and built-in call-recording, IVR capabilities to screen unknown callers, voicemail transcription, and the ability/requirement to use an email client as your SMS client. Though you then get to treat SMS and calls as device agnostic - desktop, laptop, tablet, and phone all send & recieve SMS and voice calls