Company Firewall Problems

If MyConnection PC's traceroute does not reach the end destination, it could be because a network firewall is blocking it. This will result in packet loss of 100% at one hop, and no data beyond that hop.
If this is what you are currently seeing, and the blockage occurs within the first two or three hops, then the network firewall is probably within your network.

In this case you simply need to configure it to enable ICMP. Ask your network administrator.
If the blockage occurs after more than three or four hops, the network firewall is probably located in your VoIP provider's network.

This means that you have no control over it, and you will not be able to trace the last few hops to the final destination. However, the traceroute will still show your route across the public Internet and this may be enough to diagnose faults.