Cell carrier to SMS email domain: https://support.gomotionapp.com/en/articles/407-email-to-sms-gateway-list

cell-carrier-to-email-domain.json

{
  "Alaska Communications": "msg.acsalaska.com",
  "AT&T Wireless": "txt.att.net",
  "Bell Mobility": "txt.bell.ca",
  "Bell MTS": "text.mts.net",
  "Bluegrass Cellular": "sms.bluecell.com",
  "Boost Mobile": "myboostmobile.com",
  "Cellcom": "cellcom.quiktxt.com",
  "Chatr": "pcs.rogers.com",
  "Consumer Cellular (AT&T)": "mms.att.net",
  "Consumer Cellular (T-Mobile)": "mailmymobile.net",
  "Cricket": "mms.cricketwireless.net",
  "C Spire": "cspire1.com",
  "Digicel St. Lucia": "digitextlc.com",
  "Eastlink Canada": "mms.eastlink.ca",
  "Fido": "fido.ca",
  "Freedom Mobile": "txt.freedommobile.ca",
  "FreeUP Mobile": "txt.att.net",
  "GCI": "mobile.gci.net",
  "Good2Go Mobile": "txt.att.net",
  "Google Fi": "msg.fi.google.com",
  "GreatCall": "vtext.com",
  "H2O Wireless": "txt.att.net",
  "IV Cellular (Illinois Valley Cellular)": "ivctext.com",
  "Koodo Mobile": "msg.telus.com",
  "Metro PCS": "mymetropcs.com",
  "Mint Mobile": "tmomail.net",
  "Nex-Tech": "sms.nextechwireless.com",
  "Page Plus": "vtext.com",
  "PC Mobile": "mobiletxt.ca",
  "Pioneer Cellular": "zsend.com",
  "Pure TalkUSA": "txt.att.net",
  "Republic Wireless": "text.republicwireless.com",
  "Rogers Wireless": "pcs.rogers.com",
  "SaskTel": "sms.sasktel.com",
  "SIMPLE Mobile": "mmst5.tracfone.com",
  "Solo Mobile": "txt.bell.ca",
  "Spectrum Mobile": "vtext.com",
  "Sprint": "messaging.sprintpcs.com",
  "STRATA Networks": "rinasms.com",
  "Telus Mobility": "msg.telus.com",
  "Ting (CDMA devices)": "message.ting.com",
  "Ting (GSM devices)": "tmomail.net",
  "T-Mobile": "tmomail.net",
  "Twigby": "messaging.sprintpcs.com",
  "Ultra Mobile": "mailmymobile.net",
  "Union Wireless": "mms.unionwireless.com",
  "US Cellular": "email.uscc.net",
  "Verizon": "vtext.com",
  "Viaero": "viaerosms.com",
  "Virgin Mobile": "vmobl.com",
  "Virgin Mobile Canada": "vmobile.ca",
  "Xfinity Mobile": "vtext.com"
}