On your computer:
Sign up for an account at Callcentric.com, go to IPKall.com and sign up for an account there too. (Put in your Callcentric info) IPKall will associate a phone number with your Callcentric account.
On your Coby:
Download Google Voice, Google Voice Callback and Csipsimple.
Open Csipsimple and add an account. Scroll down to Callcentric and type in the correct info.
On ur computer, go to Google voice, get a Google Voice phone number, and add the Callcentric number(The number IPKall gave you) under "Forwards Calls To:", then verify it.
On Coby, open Google voice Callback and select the callback number as the Callcentric (IPKall) number.
OF course, you can just start texting with your Google Voice app.
Hope this helps. I'll check this thread on Sunday and answer any questions.