Is there any way to get into a higher class of service - currently it appears we are only able to get 14.4kbps upload (a single GPRS time slot). Can the MTSMC-G-F be configured to use multiple GPRS time slots?

These is a class 10 modem. Class 10 supports up to 2 upload time slots. You cannot control the number of time slots used. This is controlled by the network provider.