Aside from selecting "Use Compression" there is nothing more I can set in E60. I could force G729 with my sipura, but there I have no use for it.
Truphone for example will always prioritize AMR codec, but for that they use an provisioning SMS. With Nokia's E-Series AFAIK you can use this provisioning SMS to tell it to use something other than G711. The other option would be to simply block it, forcing Nokia to take its standard next best.
Btw, could we get AMR as a codec?
