# US 10,375,127 B2 · System and method for preventing robocall voicemail deposit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,375,127 B2 - Document ID: US10375127B2 - Status: Granted - Kind: B2 - Application number: 15/690,023 - Filed: 2017-08-29 - Published: 2019-02-28 - Granted: 2019-08-06 - Earliest claimed: 2017-08-29 - Assignees: T-Mobile USA, Inc. - Applicants: T-Mobile USA, Inc. - Inventors: Homer Nicolas B. Filart - Web page: https://patentgrep.com/patent/US10375127B2 ## CPC - H04L 65/1079: {of unsolicited session attempts, e.g. SPIT} - H04L 65/1073: Registration or de-registration - H04L 65/1104: Session initiation protocol [SIP] - H04M 3/436: Arrangements for screening incoming calls {, i.e. evaluating the characteristics of a call before deciding whether to answer it (based on the calling party profile H04M3/42059; based on location H04M3/42348; based on presence H04M3/42365; diversion H04M3/54)} - H04M 3/4365: {based on information specified by the calling party, e.g. priority or subject} - H04M 3/53366: {Message disposing or creating aspects} - H04W 8/02: Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks - H04L 61/4557: Directories for hybrid networks, e.g. including telephone numbers - H04M 2203/2027: Live party detection - H04M 2203/551: Call history - H04W 8/26: Network addressing or numbering for mobility support - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems and methods for preventing a robocall from leaving a voicemail are described. When an incoming call without a history information header (HIH) destined for a subscriber is detected, the incoming call is prevented from leaving a voicemail if the subscriber does not answer the incoming call. If the incoming call has the HIH, additional determination process based on a visited network address of the subscriber is performed to determine whether the incoming call is to be prevented from leaving a voicemail. ## Claims ### Claim 1 A method for preventing an unanswered call from depositing a voicemail, the method comprising: determining whether call redirection history information is present in an attribute of the unanswered call to a user equipment (UE); and upon determining that the call redirection history is present in the attribute; determining whether a visited network address of the UE is a home global title address of the UE; determining that the UE is in a home network of the UE based on the visited network address of the UE; and preventing the unanswered call from depositing a voicemail. ### Claim 2 (depends on 1) The method of claim 1, wherein: the attribute is a SIP INVITE; and the call redirection history information is a history-info header (HIH) included in the SIP INVITE, the HIH generated by a network node comprising at least one of a mobile switching center (MSC), a MSC server (MSS), or a telephony application server (TAS). ### Claim 3 (depends on 1) The method of claim 1, wherein determining that the UE is in a home network comprises: initiating an inquiry to one of: a home location register (HLR); a home subscriber server (HSS); or a unified subscriber database (USD). ### Claim 4 (depends on 3) The method of claim 3, wherein the inquiry includes at least one of a send routing information (SRI) or an SRI for short message (SRI-SM). ### Claim 5 A non-transitory computer storage medium storing computer-readable instructions executable by a computer, that when executed by the computer, cause the computer to perform operations comprising: determining whether call redirection history information is present in an attribute of an unanswered call to a user equipment (UE); upon determining that the call redirection history is present, determining that the UE is not in a home network of the UE based on a visited network address of the UE; announcing a set of numbers to a caller of the unanswered call; requesting the caller to enter a sequence of numbers from the announced set of numbers; and upon determining that the caller failed to enter the sequence of numbers correctly, preventing the unanswered call from depositing a voicemail. ### Claim 6 (depends on 5) The non-transitory computer storage medium of claim 5, wherein: the attribute is a SIP INVITE; and the call redirection history information is a history-info header (HIH) included in the SIP INVITE, the HIH generated by a network node comprising at least one of a mobile switching center (MSC), a MSC server (MSS), or a telephony application server (TAS). ### Claim 7 (depends on 6) The non-transitory computer storage medium of claim 6, wherein the operations further comprise: upon determining that the HIH is present in the SIP INVITE; determining whether the visited network address of the UE is a home global title address of the UE. ### Claim 8 (depends on 7) The non-transitory computer storage medium of claim 7, wherein determining that the visited network address of the UE is not the home global title address of the UE comprises: initiating an inquiry to one of: a home location register (HLR); a home subscriber server (HSS); and a unified subscriber database (USD). ### Claim 9 (depends on 8) The non-transitory computer storage medium of claim 8, wherein the inquiry includes at least one of a send routing information (SRI) or an SRI for short message (SRI-SM). ### Claim 10 (depends on 5) The non-transitory computer storage medium of claim 5, wherein the set of numbers is randomly generated. ### Claim 11 A system configured to prevent an unanswered call to a user equipment (UE) from depositing a voicemail, the system comprising: one or more processors; memory communicatively coupled to the one or more processors, the memory comprising a plurality of modules communicatively coupled to each other, the plurality of modules comprising: a determination module configured to determine whether call redirection history information is present in an attribute of the unanswered call, wherein the determination module is further configured to, upon determining that the call redirection history information is present in the attribute: determine whether a visited network address of the UE is a home global title address of the UE; and determining that the UE is in a home network of the UE based on the visited network address of the UE; and a prevention module configured to prevent the unanswered call from depositing a voicemail upon determining, by the determination module, that the call redirection history information is not present or upon determining that the UE is in the home network. ### Claim 12 (depends on 11) The system of claim 11, wherein: the attribute is a SIP INVITE; and the call redirection history information is a history-info header (HIH) included in the SIP INVITE, the HIH generated by a network node comprising at least one of a mobile switching center (MSC), a MSC server (MSS), or a telephony application server (TAS). ### Claim 13 (depends on 11) The system of claim 11, wherein the determination module is further configured to determine whether the visited network address of the UE is the home global title address of the UE by initiating an inquiry to one of: a home location register (HLR); a home subscriber server (HSS); or a unified subscriber database (USD). ### Claim 14 (depends on 13) The system of claim 13, wherein the inquiry includes at least one of a send routing information (SRI) or an SRI for short message (SRI-SM). ### Claim 15 (depends on 11) The system of claim 11, wherein the plurality of modules further comprises a randomizer module, the randomizer module configured to: announce a set of numbers to a caller of the unanswered call; request the caller to enter a sequence of numbers from the announced set of numbers; determine whether the caller has correctly entered the sequence of numbers; and prevent the unanswered call from depositing a voicemail upon determining that the caller failed to enter the sequence of numbers correctly.