A telephone system determining if a certain fixed telephone or fixed data network connection should be established, comprising: a) means for reading individual parameters capable of reading a mobile phone number, b) means for reading a price capable of reading a price of a fixed telephone or fixed data network connection, c) a network affiliation inquiry module for gathering information of a mobile network from a mobile network affiliation database, d) a tariff determination module for gathering information of a mobile network from a tariff database, e) means for estimating an individual price for a mobile phone connection capable of assigning a table of tariffs to the individual parameter(s) provided by the means for reading the individual parameters by using the network affiliation inquiry module and/or the tariff determination module and capable of estimating an individual price for a mobile phone connection from the table of tariffs to a certain destination at a certain time, f) means for estimating an individual maximal price capable of estimating an individual maximal price to the certain destination at the certain time from the individual price for a mobile phone connection provided by the means for estimating an individual price, wherein the individual maximal price is the price a user is probably willing to pay for the fixed telephone or fixed data network connection, and wherein the estimated individual maximal price is less than the estimated individual price to the certain destination at the certain time, g) means for comparing the estimated individual maximal price to the certain destination at the certain time with the price of the fixed telephone or fixed data network connection to the certain destination at the certain time, and h) means for outputting the result of the comparison. a) means for reading individual parameters capable of reading a mobile phone number, b) means for reading a price capable of reading a price of a fixed telephone or fixed data network connection, c) a network affiliation inquiry module for gathering information of a mobile network from a mobile network affiliation database, d) a tariff determination module for gathering information of a mobile network from a tariff database, e) means for estimating an individual price for a mobile phone connection capable of assigning a table of tariffs to the individual parameter(s) provided by the means for reading the individual parameters by using the network affiliation inquiry module and/or the tariff determination module and capable of estimating an individual price for a mobile phone connection from the table of tariffs to a certain destination at a certain time, f) means for estimating an individual maximal price capable of estimating an individual maximal price to the certain destination at the certain time from the individual price for a mobile phone connection provided by the means for estimating an individual price, wherein the individual maximal price is the price a user is probably willing to pay for the fixed telephone or fixed data network connection, and wherein the estimated individual maximal price is less than the estimated individual price to the certain destination at the certain time, g) means for comparing the estimated individual maximal price to the certain destination at the certain time with the price of the fixed telephone or fixed data network connection to the certain destination at the certain time, and h) means for outputting the result of the comparison.