IP telephony for business is more than just the technologies that make communication with customers considerably easier. It is an opportunity to communicate effectively, manage calls and use all IP telephony advantages. IP telephony services include a variety of convenient and at the same time helpful solutions, for example, adding phone numbers to DNC list. We have developed this function and created the capability to temporarily add a phone number to this list. Phone numbers can be added manually or with the help of the status allowing to include a phone number into the list for a specific amount of time.