I've been following a VoIP startup Voxox for a few years now, waiting for a mature OS X app to be developed. On a recent visit to their site, I found that indeed a Mac desktop application was now available in addition to iOS, Android and a long-standing Windows desktop application.
Voxox centralizes all your communications, whether voice or social media. When you register you are provided a centralized (USA) phone number, but can purchase additional numbers in one or more local areas. You can present these numbers to your contacts, and through the Voxox application, receive calls, texts, and social media at any of a number of devices or phone you choose. For instance, if you travel and pick up a local SIM at your destination, your contacts still call or text your usual number, but it would be forwarded to your new number. If your cottage is outside your carrier's cell service area, but has a landline - your Voxox number can be switched to forward calls there. Best of all, you can create a ranking of numbers to try, so if you step away froth cottage to pick up groceries, calls can automatically be switched to your cellphone.
Another handy option is to create a list of phone numbers Voxox calls sequentially or simultaneously to find you. When a caller dials your Voxox number they are greeted by a pleasant voice stating they are searching for <your name>, and a ring tone sounds until either a number is answered, or the search fails to find an answered phone from your list, and the caller is directed to voice mail. The voice mail is transcribed and sent to you as text.
The Voxox app also manages your texts, and social media interactions. SMS are forwarded to your phone or tablet, and you can keep tabs on all your social media contacts through the app on your phone, tablet or desktop. Voxox also translates texts between any of 60 languages!
Outgoing long distance calls through Voxox are managed through callback process to keep your long distance call at local rates. You send the number you want to call to the system, and it calls you back and connects you to your party. You can also fax documents from your phone to your contacts. Calls and texts between Voxox users are free.
For those who change phone numbers through the day, week or month, or even for annual vacations outside your carrier's coverage area, Voxox is worth a look.