An address book server (403, 502) for relaying or transferring a call, the call being from a first phone terminal (406, 505) to the address book server (403, 502), to a second phone terminal or a third phone terminal of a recipient, the address book server (403, 502) configured to: store identification information of the second phone terminal and identification information of a user of the second phone terminal in association with each other, and store identification information of the third phone terminal and identification information of a user of the third phone terminal in association with each other; receive the call from the first phone terminal (406, 505); search for the identification information of the second phone terminal or the third phone terminal of the recipient that is associated with either: (i) the identification information of the user identified by voice recognition on voice information received from the first phone terminal (406, 505) as an instruction of a user of the first phone terminal (406, 505), or (ii) the identification information of the user received from the first phone terminal (406, 505) as the instruction, the identification information being in a form of an Integrated Services Digital Network, ISDN, sub-address or a Dual-Tone Multi-Frequency, DTMF, signal; and make a call to the second phone terminal or the third phone terminal of the recipient corresponding to the searched identification information so as to relay or transfer, to the second phone terminal or the third phone terminal of the recipient, the call from the first phone terminal (406, 505), wherein the first phone terminal (406, 505) and the second phone terminal are cellular phone terminals, the user of the second phone terminal is different from the user of the third phone terminal, the recipient is either the user of the second phone terminal or the user of the third phone terminal. store identification information of the second phone terminal and identification information of a user of the second phone terminal in association with each other, and store identification information of the third phone terminal and identification information of a user of the third phone terminal in association with each other; receive the call from the first phone terminal (406, 505); search for the identification information of the second phone terminal or the third phone terminal of the recipient that is associated with either: (i) the identification information of the user identified by voice recognition on voice information received from the first phone terminal (406, 505) as an instruction of a user of the first phone terminal (406, 505), or (ii) the identification information of the user received from the first phone terminal (406, 505) as the instruction, the identification information being in a form of an Integrated Services Digital Network, ISDN, sub-address or a Dual-Tone Multi-Frequency, DTMF, signal; and (i) the identification information of the user identified by voice recognition on voice information received from the first phone terminal (406, 505) as an instruction of a user of the first phone terminal (406, 505), or (ii) the identification information of the user received from the first phone terminal (406, 505) as the instruction, the identification information being in a form of an Integrated Services Digital Network, ISDN, sub-address or a Dual-Tone Multi-Frequency, DTMF, signal; and make a call to the second phone terminal or the third phone terminal of the recipient corresponding to the searched identification information so as to relay or transfer, to the second phone terminal or the third phone terminal of the recipient, the call from the first phone terminal (406, 505), wherein the first phone terminal (406, 505) and the second phone terminal are cellular phone terminals, the user of the second phone terminal is different from the user of the third phone terminal, the recipient is either the user of the second phone terminal or the user of the third phone terminal.