# US 2023/0055014 A1 · Apparatus, method and computer program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0055014 A1 - Document ID: US20230055014A1 - Status: Published application - Kind: A1 - Application number: 17/797,349 - Filed: 2020-02-06 - Published: 2023-02-23 - Earliest claimed: 2020-02-06 - Assignees: Nokia Technologies Oy - Applicants: Nokia Technologies Oy - Inventors: Peter LEIS; Lazaros GKATZIKIS - Web page: https://patentgrep.com/patent/US20230055014A1 ## CPC - H04L 65/4061: Push-to services, e.g. push-to-talk or push-to-video - H04L 65/1069: Session establishment or de-establishment - H04L 65/1104: Session initiation protocol [SIP] - H04W 4/10: Push-to-Talk [PTT] or Push-On-Call services - H04W 4/16: Communication-related supplementary services, e.g. call-transfer or call-hold - H04L 61/103: across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP] - H04L 2101/365: Application layer names, e.g. buddy names, unstructured names chosen by a user or home appliance name - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract An apparatus comprising means for performing: receiving, from a first client, a call request comprising address information for calling at least one second client, the address information comprising a Functional Alias, wherein the Functional Alias is activated by the at least one second client; in response to receiving the call request at the apparatus, sending, to a server, a request to re-solve the Functional Alias to at least one Mission Critical Push to Talk Identifier of the at least one second client that has activated the Functional Alias; receiving, at the apparatus from the server, the at least one Mission Critical Push to Talk Identifier of the at least one second client; sending, from the apparatus, a call request to the at least one second client using the at least one Mission Critical Push to Talk Identifier of the at least one second client. ## Claims ### Claim at position 1 -16. (canceled) ### Claim 17 An apparatus, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a first client, a call request comprising address information for calling at least one second client, the address information being a Functional Alias, wherein the Functional Alias is activated by the at least one second client; in response to receiving the call request at the apparatus, send, to a server, a request to resolve the Functional Alias to at least one Mission Critical Push to Talk Identifier of the at least one second client that has activated the Functional Alias; receive, at the apparatus from the server, the at least one Mission Critical Push to Talk Identifier of the at least one second client; and send, from the apparatus, a call request to the at least one second client using the at least one Mission Critical Push to Talk Identifier of the at least one second client. ### Claim 18 (depends on 17) The apparatus as claimed in claim 17, wherein the request to resolve the Functional Alias comprises a Session Initiation Protocol message comprising the Functional Alias; and wherein the receiving, at the apparatus from the server, the at least one Mission Critical Push to Talk Identifier comprises receiving a Session Initiation Protocol message comprising the at least one Mission Critical Push to Talk Identifier. ### Claim 19 (depends on 17) The apparatus as claimed in claim 17, wherein the request to resolve the Functional Alias comprises a database query; and wherein the database query comprises the Functional Alias as a query parameter. ### Claim 20 (depends on 17) The apparatus as claimed in claim 17, wherein the instructions are further configured to, when executed by the at least one processor, cause the apparatus at least to: in response to receiving, at the apparatus from the server, two or more Mission Critical Push to Talk Identifiers of the at least one second client, determine, based on a policy, whether to: send a call request to each Mission Critical Push to Talk Identifier of the two or more Mission Critical Push to Talk Identifiers; or to select one Mission Critical Push to Talk Identifier of the two or more Mission Critical Push to Talk Identifiers to send the call request. ### Claim 21 (depends on 17) The apparatus as claimed in claim 17, wherein the instructions are further configured to, when executed by the at least one processor, cause the apparatus to at least: determine, based on the call request received from the first client, that routing of the incoming call request is to be based on the Functional Alias. ### Claim 22 (depends on 17) The apparatus as claimed in claim 17, wherein the instructions are further configured to, when executed by the at least one processor, cause the apparatus at least to: determine, based on the Functional Alias, to which server of two or more servers to send the request to resolve the Functional Alias. ### Claim 23 (depends on 17) The apparatus as claimed in claim 17, wherein the apparatus comprises a Mission Critical Push to Talk controlling or participating server. ### Claim 24 (depends on 17) The apparatus as claimed in claim 17, wherein the sending, to the server and in response to receiving the call request at the apparatus, the request to resolve the Functional Alias to the at least one Mission Critical Push to Talk Identifier of the at least one second client that has activated the Functional Alias is performed on a call by call basis. ### Claim 25 A method, comprising: receiving, from a first client, a call request comprising address information for calling at least one second client, the address information being a Functional Alias, wherein the Functional Alias is activated by the at least one second client; in response to receiving the call request, sending, to a server, a request to resolve the Functional Alias to at least one Mission Critical Push to Talk Identifier of the at least one second client that has activated the Functional Alias; receiving, from the server, the at least one Mission Critical Push to Talk Identifier of the at least one second client; and sending a call request to the second client using the at least one Mission Critical Push to Talk Identifier of the at least one second client. ### Claim 26 (depends on 25) The method as claimed in claim 25, wherein the request to resolve the Functional Alias comprises a Session Initiation Protocol message comprising the Functional Alias; and wherein the receiving, from the server, the at least one Mission Critical Push to Talk Identifier comprises receiving a Session Initiation Protocol message comprising the at least one Mission Critical Push to Talk Identifier. ### Claim 27 (depends on 25) The method as claimed in claim 25, wherein the request to resolve the Functional Alias comprises a database query; and wherein the database query comprises the Functional Alias as a query parameter. ### Claim 28 (depends on 25) The method as claimed in claim 25, wherein the method further comprises, in response to receiving, from the server, two or more Mission Critical Push to Talk Identifiers of the at least one second client: determining, based on a policy, whether to send a call request to each Mission Critical Push to Talk Identifier of the two or more Mission Critical Push to Talk Identifiers, or to select one Mission Critical Push to Talk Identifier of the two or more Mission Critical Push to Talk Identifiers to send the call request. ### Claim 29 (depends on 25) The method as claimed in claim 25, wherein the method further comprises: determining, based on the call request received from the first client, that routing of the incoming call request is to be based on the Functional Alias. ### Claim 30 (depends on 25) The method as claimed in claim 25, wherein the method further comprises: determining, based on the Functional Alias, to which server of two or more servers to send the request to resolve the Functional Alias. ### Claim 31 (depends on 25) The method as claimed in claim 25, wherein the method is performed by a Mission Critical Push to Talk controlling or participating server. ### Claim 32 (depends on 25) The method as claimed in claim 25, wherein the sending, to the server and in response to receiving the call request, the request to resolve the Functional Alias to the at least one Mission Critical Push to Talk Identifier of the at least one second client that has activated the Functional Alias is performed on a call by call basis. ### Claim 33 A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least: receiving, from a first client, a call request comprising address information for calling at least one second client, the address information being a Functional Alias, wherein the Functional Alias is activated by the at least one second client; in response to receiving the call request at the apparatus, sending, to a server, a request to resolve the Functional Alias to at least one Mission Critical Push to Talk Identifier of the at least one second client that has activated the Functional Alias; receiving, at the apparatus from the server, the at least one Mission Critical Push to Talk Identifier of the at least one second client; and sending, from the apparatus, a call request to the at least one second client using the at least one Mission Critical Push to Talk Identifier of the at least one second client.