Sip dialer for Android

I am in need of a skilled Android developer to create a sip dialer application for me. The application should have the following features:

- Call recording
- Call transfer
- Video calling (optional, but preferred)

I am unsure if I require any form of encryption for the calls, so the developer should have experience in implementing secure communication protocols.

While I do not have a specific design in mind, I would prefer a user-friendly interface for the dialer. The developer should have experience in creating intuitive and visually appealing user interfaces.

Overall, I am looking for a reliable and experienced Android developer who can create a high-quality sip dialer application with the aforementioned features and a user-friendly interface.