You can use a Skype USB adapter, like
USB Voip Telbox
USB Voip Telbox allows you to use your regular home phone for Skype as well as any VOIP interface. When your regular phone is connected with this adapter, you can dial and receive calls via Skype and VOIP without the need to buy a Skype phone. This adapter allows any desktop/cordless phone to operate as a dialer and speakerphone for Skype.
Main features- Fully integrated with Skype for making & receiving calls.
- All incoming calls to your Skype phone number will be forwarded to your regular phone and will ring just the same as your regular phone call.
- Just pick up the phone and dial, SkypeOut will be automatically detected and used for long distance call.
USB Voip Telbox is very cheap. But it requires you to have your computer to be working when you make a call. And it uses SkypeMate software, which may not work on some computers.