Yes, bit-banged.

The ISD1700 chips are tempermental to say the least. I have it working fine in my project, but there are some undocumented problems with this chip. Overall the documentation is inconsistent/poor and difficult to find current versions. I found out after a year of using this chip that I had the outdated datasheets.

Also, the development systems were redesigned when it moved from Winbond to Nuvoton. And the Winbond hardware does not work with Nuvoton software, so if you were unlucky to buy the early ones, you get to buy it all over again (or you just design your own). I like this chip, but Nuvoton does not help with the problems.

As for SPI, I have worked with the ISD1700 and another SPI device connected to the same PIC micro. Each device uses the complete opposite SPI communications format. The logic levels are inverted and the MSB/LSB is reversed on each device. I don't know which way is "standard" for SPI. So you may want to try changing MSB/LSB data and try inverting various signals (clock, data, chip select).

Otherwise the code examples in previous posts on this thread should be a good head start.