I use a SIP provider for the landline at home. When on vacation I want to be able to make outbound calls with my landline number. I know this can be done, but I have no idea how. Does anyone here have some pointers for required hardware, software and configuration?
You can install Linphone from the Fdroid repository, and register it with your SIP provider as an extension. How you set it up as an extension will vary by the provider.