Voxbone offers good quality DIDs that you map to any SIP address you want in your account portal (I map mine to
usernumber@voxalot.com but I can change it any time and the routing change takes effect immediately). You pay by the month but you can keep it as long as the company is around and always point it to your latest SIP address or use a SIP Broker alias with a Dynamic IP address service to bypass providers entirely. Their price is $11.00 USD setup and a flat $12.50 USD/month thereafter (charged on the 1st day of the month) with unlimited incoming on two channels.