Hi.
Thanks for your message. Your input is really appreciated.
I understand that might be the case, as security might be a factor in selecting a landline phone number.
However, all digital landline provider can and allow (almost promote) picking a landline number. (e.g. Skype, Vectone, Google Voice <US> etc.)
Which then, you can port out from their company to a landline, should you choose to do so? This has been done in the US, UK and in some countries on the continent. Whist I think security might be a factor, I do not feel is the determinant one, in this particular example. But I'm more than open to see an aspect of this request, beyond my own opinion or experience.
I would suggest to Google "pick your landline number" and see how much this is promoted. I'm not sure all of them, but I guarantee a couple of years ago I've ported out a Skype landline number to a BT non-virtual phone. GDPR might now prevent this, but this was tested, executed and accomplished successfully two years ago, max.

Although if it can be done virtually why would it be such a major risk factor? More so that VM uses the router for this landline numbers, hence, I assume they are VOIP-ish as well as the one in the above example. Am I wrong?
Thanks and regards,
Alexander