Tested them out and got to say that I am not impressed.

1 they running MERA Softswitch which is extremely problematic (can’t make calls, outages, unreliable)
2 does not support SIP reinvite for RTP stream therefore can introduce additional lag and cause audio to breakup.
3 They try to help out and support their clients.

All in all, since they are using a product (MERA) that is inferior, I would recommend not to use their service until either they get a proper softswitch from PortaOne or others and can properly configure it.