Thanks for the response. Loaded wireshark and saw that the RTP packets are routed through the Voip provider servers, hence the charge of the call.
Just for interest sake, i did a calculation what the actual cost is to terminate a call.
Say the Provider pays R30.00 per Gig, it works out to +- R0.03 per meg.To terminate a call uses +- 6000 bytes.
With 1 Meg you can terminate +- 170 calls which works out to R0.00018 per call. With 1Gig they can terminate 174080 calls.
This does not include the RTP portion, only to terminate the call.