Yes, we plan to make some modifications to take Header Compression into account on our online calculators. The difficulty is, we are uncertain whether there is an industry standard. I have seen Cisco quote a scheme which reduces the headers to 2-4 bytes, but I don’t know if this is a Cisco proprietary system, and whether it can be used in all circumstances.
VoIP is a difficult subject to research. If you find any information, please share it on this Forum.
The Header compresion is recomended only for link of low speed, for hing spedd above 256 Kbps is not recomended.
Furtheremore, it required a loit of CPU cycles, that can degrade the performace of the Gateway.