I am currently developing my own VOIP service and would love to have a branded basic SIP phone to go with it. What is a good starting point? Being a good developer, I am lazy and would not like to reinvent the wheel . Any open battle-tested libraries available for use? Or possibly applications I will just need to skin? I have had an inconclusive look around and I would be grateful for any tips from someone who has developed his/her own phone before.