I started playing with VoIP last week, here's what I would recommend people do.
1) Create your voip.ms account
Be aware that the password you enter at this time will be your Customer Portal and your Main SIP/IAX Passwords. I recommend you change both to a complicated password (the webpage tells you if your password is complex or not) if you went with a simple one. For this go to Main Menu > Account Settings
2) Add some money by going to Finances > Add Funds
Install a Softphone on your computer. I installed X-Lite 4 for no particular reason other than this is what I found first.
3) Configure X-Lite 4 with voip.ms
Open Softphone > Account Settings and enter the following (my comments in brackets):
Account name: VOIPms (any name you want, I like naming things after the server I will connect to).
User ID: <your SIP Username> (on voip.ms, go to Main Menu > Account Information)
Domain: seattle.voip.ms (select the server that's closest to you from the list of voip.ms Servers - I'm in Vancouver so Seattle it is)
Password: <SIP Password> (the one I asked you to change)
Display name: <Your name>
If all goes well, once you click OK the softphone should 'register' with voip.ms. If the green Call button letters are white, you're good.
Ensure you're using your headset on the client. Go to Softphone > Preferences > Devices and ensure that you are using the correct speaker, microphone amd HID device.
4) Switch to your web broswer and go to your Account Settings (Main Menu > Account Settings), look for the row that says: CallerID Number - hover on top of the (?) and see what it says - enter your current phone number (no spaces or dots or hyphens). Once you enter your phone number, press apply (just to the right of the box).
You should now be able to make phone calls from your softphone. And people who get them will see the number you entered in the CallerID field.
If you go to your Account Settings (voip.ms), you can play with the different options for your main SIP account - of interest here would be the routing (value or premium) options.
If you wish to be able to receive calls then you need to get a DID, but thatís another story.