A protection against unsolicited communication for Internet Protocol Multimedia Subsystem, PUCI, system including: a call session control function, CSCF,; and a plurality of PUCI application servers (501, 502, 503, 504), wherein each PUCI application server (501; 502; 503; 504) has a dynamic call routing capability based on special PUCI information included in an Internet Protocol Multimedia Subsystem, IMS, / Session Initiated Protocol, SIP, header, wherein the system is adapted to evaluate as to whether a communication received from a user equipment is an unsolicited communication; the CSCF is adapted to decide on routing toward the plurality of PUCI application servers (501, 502, 503, 504) based on the evaluation; and the plurality of PUCI application servers (501, 502, 503, 504) is adapted to execute the routing based on the decision, wherein the system is adapted to implement the following: forwarding an INVITE from the user equipment to the CSCF; executing a PUCI service in the CSCF; forwarding the INVITE in light of an initial filter criteria from the CSCF to a first PUCI application server; executing a PUCI Test 1 in the first PUCI application server, thus producing a result indicating a probability of occurrence of an unsolicited call; sending back the INVITE including the result of the PUCI Test 1 from the first PUCI application server to the CSCF; evaluating the result so as to forward the INVITE to a second PUCI application server suitable for further testing; executing a PUCI Test 2 in the second PUCI application server, thus producing a result indicating a further probability of the occurrence of the unsolicited call; sending back the INVITE including the result of the PUCI Test 2 from the second PUCI application server to the CSCF; and evaluating both the results so as to reject the unsolicited call. a call session control function, CSCF,; and a plurality of PUCI application servers (501, 502, 503, 504), wherein each PUCI application server (501; 502; 503; 504) has a dynamic call routing capability based on special PUCI information included in an Internet Protocol Multimedia Subsystem, IMS, / Session Initiated Protocol, SIP, header, wherein the system is adapted to evaluate as to whether a communication received from a user equipment is an unsolicited communication; the CSCF is adapted to decide on routing toward the plurality of PUCI application servers (501, 502, 503, 504) based on the evaluation; and the plurality of PUCI application servers (501, 502, 503, 504) is adapted to execute the routing based on the decision, forwarding an INVITE from the user equipment to the CSCF; executing a PUCI service in the CSCF; forwarding the INVITE in light of an initial filter criteria from the CSCF to a first PUCI application server; executing a PUCI Test 1 in the first PUCI application server, thus producing a result indicating a probability of occurrence of an unsolicited call; sending back the INVITE including the result of the PUCI Test 1 from the first PUCI application server to the CSCF; evaluating the result so as to forward the INVITE to a second PUCI application server suitable for further testing; executing a PUCI Test 2 in the second PUCI application server, thus producing a result indicating a further probability of the occurrence of the unsolicited call; sending back the INVITE including the result of the PUCI Test 2 from the second PUCI application server to the CSCF; and evaluating both the results so as to reject the unsolicited call.