Hi,
I am an Electronics and computer science engineer, I have experience working with various prototyping boards, Raspberry Pi, Arduino, mbed (ARM proto board)... as well as developing custom PCBs, you can find some of my projects on my portfolio.
I have set up VoIP for a client in the past, so I know what I'm talking about, hence the higher bid.
I think using the Pi offer the possibility to integrate cool features like amazon echo for ex... would love to talk to you more, and get going with this project.
I pride myself on ensuring that the customer is satisfied with the quality of the work and strive to sustain good communication and complete the project (5-star reviews/ 100% completion rate)
Looking forward to working with you.
Regards,
Nabil