What is hvolte?

VoLTE networks run at 4G speeds, for better voice and data quality than 2G/3G networks. hVoLTE, or hybrid VoLTE is a mode of operation that allows LTE networks and existing circuit-switched networks to coexist. hVoLTE, or hybrid VoLTE, is a mode of operation that allows the two technologies to coexist and testing this coexistence on devices is critical to. hVoLTE, or hybrid VoLTE, is a mode of operation that allows the two technologies to co-exist. Voice over Long-Term Evolution (VoLTE) is a standard high-speed wireless communication for mobile phones and data terminals, including Internet of things. Involved in log analysis and Debugging related to chipset/ network Issues • Perform Verizon VoLTE, SRVoTE, hVoLTE testing • Working on new features for LTE.

AT+QCFG=“ims” +QCFG: “ims”,1,0 OK

AT+COPS? +COPS: 0,0,“AT&T 4G”,7 OK

Not Mexican network on the list. Maybe this is the problem? AT+QMBNCFG=“List” +QMBNCFG: “List”,0,1,1,“ROW_Generic_3GPP”,0x0501081F,202108201 +QMBNCFG: “List”,1,0,0,“VoLTE-ATT”,0x0501033C,202105171 +QMBNCFG: “List”,2,0,0,“hVoLTE-Verizon”,0x05010141,202011021 +QMBNCFG: “List”,3,0,0,“Sprint-VoLTE”,0x05010205,202010201 +QMBNCFG: “List”,4,0,0,“Commercial-TMO_VoLTE”,0x05010505,202106241 +QMBNCFG: “List”,5,0,0,“Telus-Commercial_DO”,0x0580F601,202105061 +QMBNCFG: “List”,6,0,0,“Commercial-SBM”,0x05011C18,202004211 +QMBNCFG: “List”,7,0,0,“Commercial-DT”,0x05011F1C,202106171 +QMBNCFG: “List”,8,0,0,“Reliance_OpnMkt”,0x05011B38,202003251 +QMBNCFG: “List”,9,0,0,“TF_Germany_VoLTE”,0x05010C1B,202004151 +QMBNCFG: “List”,10,0,0,“TF_Spain_VoLTE”,0x05010CFA,202106171 +QMBNCFG: “List”,11,0,0,“Volte_OpenMkt-Commercial-CMCC”,0x05012071,202102221 +QMBNCFG: “List”,12,0,0,“VoLTE_OPNMKT_CT”,0x050113FC,202105131 +QMBNCFG: “List”,13,0,0,“CU-VoLTE”,0x05011508,202109101 +QMBNCFG: “List”,14,0,0,“Telstra-Commercial_VoLTE”,0x0580079E,202105192 +QMBNCFG: “List”,15,0,0,“Commercial-KDDI”,0x0501071D,202011192 +QMBNCFG: “List”,16,0,0,“Commercial-DCM”,0x05010D17,202104121 +QMBNCFG: “List”,17,0,0,“Commercial-SKT”,0x05012715,202103121 +QMBNCFG: “List”,18,0,0,“Commercial-KT”,0x05012C0D,202108241 +QMBNCFG: “List”,19,0,0,“Commercial-LGU”,0x05012626,202108241 +QMBNCFG: “List”,20,0,0,“Commercial-USCC”,0x0504FC40,202011111 +QMBNCFG: “List”,21,0,0,“Optus-Commercial_VoLTE”,0x05800CA2,201910241 +QMBNCFG: “List”,22,0,0,“STC_Saudi_VoLTE”,0x0501FE01,201912231 +QMBNCFG: “List”,23,0,0,“Commercial-Rogers”,0x05018821,202108021

OK

AT+QMBNCFG=“AutoSel” +QMBNCFG: “AutoSel”,1

During the call:

AT+COPS? +COPS: 0,0,“AT&T”,2

See that number 2 means VoLTE is disabled or not voLTE session at all.