It contains utility methods.

This class can be used to remove illegal characters from descriptors before dialing. However, it shouldn't be done before you have ensured that string is acceptable by application specific grammar.

Thus, you should process as follows: 1. Check that string is acceptable. (application specific) 2. If not, stop. Otherwise continue. 3. Convert to string acceptable by phoneclient - typically, you just have to remove invalid characters. 4. Do whatever you wish with the string, e.g. dial.