1. Quality not as good as most open SIP service prividers (such as voipstunt, vbuzzer...)
2. Poor customer service and poor technical support. My incoming call has problem (I have to reboot the ATA box everyday to make incoming call going through), but they haven't fixed it for 4 months. I had (actually other people too) problem to call 613 area code a few months ago, they took 2 months to fix it.
3. Fake China call-in number. Don't expect people in China can call that so-called number to reach you - it has been blocked by carriers in China.
4. Some features not working as advertised, such as call transfer.
5. Easy to order but hard to quit. You will get high penalty if you fail to follow tough conditions and rules, which are not told you when you order it.
6. Cheaper for intensive user only. Most people do not speed $30/month with regular low-cost long distance company.