John,
There is no API/SDK for Call Center functionality in IPCC Express in the same way as in IPCC Enterprise.
For CTI integration, in IPCC Express, you can only use the macro functions in IPCC Express Enhaneced or Premium.
You can integarte phone functions (call, anwser, transfer) through JTAPI, but there is no way to use an API for login, ready, etc.
Hope this helps,
Juan Luis