Your "115kbs" is a falsehood in that it is not the true figure - it's the DTE version.
If you go into the Modem's Properties from Control Panel or Device Manager and, in the Extra Settings box, insert W2 you will get the true speeds.
Even so 31.2kbps is not good - try downloading the latest Intel driver for your modem from a source such as:
(don't know your modem's manufacturer but the Intel driver is suitable for most models).
Also set the Maximum Port speed to 115200 if this is not already the case.