Hi there!
I’m quite new to IP telephony, and our company wants to change the default application that makes our Polycom IP Phones work, to a newly developped one. Can this be done, can we modify or change the default sip.ld and develop our new one? What framework do we need to do this?
Thanks in advance!
Sorry…I think i misplaced that question. Which forum it should be in ? 
What exactly do you want done ? If you want to change the behavior of the phone a lot can be done in the config files. If you want to change how the phones work you would need to contact Polycom. Good luck with getting the source code from them 
The latter one is what I want to do. And is there any open source IP phones, which can be reprogrammed like this? Because SIP application development stacks are exist, which are told to be able to build a new SIP app to run the IP phone…
I have no idea where to look for it. There open stacks for SIP but I doubt anything that will work for Polycom.