A system for establishing a call using a single identifier, said system comprising a registry device, a call server, and two or more communication devices (11, 12) connected to a communication network, wherein the registry device is configured to: receive contact information relating to a single identifier or a range of identifiers from an uploading device, the contact information comprising at least two call protocols of contacting a communication device associated with the identifier, store the contact information received from the uploading device, on request from the call server for contact information relating to an identifier, retrieve the stored contact information and transmit a message comprising the contact information, the call server is configured to: receive a request from a first communication device to establish a call to a second communication device associated with the single identifier, request from the registry device contact information relating to the single identifier, receive the contact information relating to the single identifier from the registry device, and establish a call between the first communication device and the second communication device associated with the identifier using one of the at least two call protocols of contacting the second communication device; and wherein the call server, if failing on establishing a call between the first communication device and the second communication device associated with the identifier using one of the at least two call protocols of contacting the second communication device, is configured to establish the call using a second of the at least two call protocols of contacting the second communication device. the registry device is configured to: receive contact information relating to a single identifier or a range of identifiers from an uploading device, the contact information comprising at least two call protocols of contacting a communication device associated with the identifier, store the contact information received from the uploading device, on request from the call server for contact information relating to an identifier, retrieve the stored contact information and transmit a message comprising the contact information, receive contact information relating to a single identifier or a range of identifiers from an uploading device, the contact information comprising at least two call protocols of contacting a communication device associated with the identifier, store the contact information received from the uploading device, on request from the call server for contact information relating to an identifier, retrieve the stored contact information and transmit a message comprising the contact information, the call server is configured to: receive a request from a first communication device to establish a call to a second communication device associated with the single identifier, request from the registry device contact information relating to the single identifier, receive the contact information relating to the single identifier from the registry device, and establish a call between the first communication device and the second communication device associated with the identifier using one of the at least two call protocols of contacting the second communication device; and wherein the call server, if failing on establishing a call between the first communication device and the second communication device associated with the identifier using one of the at least two call protocols of contacting the second communication device, is configured to establish the call using a second of the at least two call protocols of contacting the second communication device. receive a request from a first communication device to establish a call to a second communication device associated with the single identifier, request from the registry device contact information relating to the single identifier, receive the contact information relating to the single identifier from the registry device, and establish a call between the first communication device and the second communication device associated with the identifier using one of the at least two call protocols of contacting the second communication device; and wherein the call server, if failing on establishing a call between the first communication device and the second communication device associated with the identifier using one of the at least two call protocols of contacting the second communication device, is configured to establish the call using a second of the at least two call protocols of contacting the second communication device.