Personally, I have never had good luck with the Counterpath products.
I started testing the X-Lite version 3 about 5 years ago. Sometimes it was ok; other times it was just trouble. Then, I upgraded to their paid-for eyebeam (around the same time period), and it again was no better than the X-Lite 3. I requested they refund my money on the eyebeam.... for me, it was a waste of money.
About 2 years ago, I started using the 3CXPhone 4.0 softphone for direct connect to my various VoIP providers that I test with. Once I figured out a few configuration quirks, it was great. It works with every VoIP provider I have connected it to. It doesn't crash on me like the X-Lite did. I wrote a blog on the 3CXPhone ver. 4 and deemed it
my Top Pick in Softphones.
Recently, I decided to give X-Lite a 2nd chance (or is it a 3rd or 4th chance) and installed their new X-Lite version 4.0.
Same thing all over again, but worse. It crashes constantly on my Windows XP SP3 and Vista PC's. (...I do hope to upgrade to Win 7 soon
).
So, I will be soon testing the 3CXPhone version 5. If version 5 is at least as good as version 4, then I don't think you can go wrong.