Well.. it depends where you want that softkey... if in application context, it's nothing complex.. you just use axl's updateLine to set the callforwardall (and you need to be aware that there's no validation being done that way... e.g if your cfwdall css allows to reach only internal destinations, you can still program a cfwdall to an external destination using updateLine.. and then if you call the line, the caller gets a fast busy).. alternatively, you could use tapi/jtapi which does perform validity checking (but doesn't tell you if the forward has failed because css blocks it, or because there was another error). Since you want to cfwdall to voicemail, that's a checkbox so updateLine is your prefered method.. it allows you to set that checkbox and we'll just assume the phones are programmed to allow cfwdall to voicemail.
However, if you want that softkey in the phone context (so e.g. on the 4th position after new call, redial and cfwd softkeys) then you're out of luck at this point. Well.. not quite.. you could have an idle url which replaces the idle phone context.. but that means you'd have to create an image which shows the phone screen as it is in idle mode (means loading the background image, figuring out the softkey profile and duplicating all the softkey options, loading the line key labels and creating the image to match the deafault screen.. there's an example for something like that in the ip phone services sdk.. however, I personally consider this to be too much effort for little gain) so I'd wait a bit, because with the next phone load, you'll finally have the ability to run java midlets on the phones, and I presume that this could give us the ability to add our own softkeys to the phone context and have them launch our own code. I can't guarantee that this is how it will work.. but I'm really hoping because the inability to add application softkeys to the phone context is really a thorn in your backside if you want to create user friendly apps..
