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The AT&T SIM still talks to AT&T regardless of what network you are connected to. It has the full international number for the AT&T SMSC hardcoded into it so it
by kingcharles 5y ago
The AT&T SIM still talks to AT&T regardless of what network you are connected to. It has the full international number for the AT&T SMSC hardcoded into it so it can correctly route the message it is sending.
- vadfa 5y agoMost operators have a whitelist of SMSCs that they will let you use. Some even ignore the SMSC field and always route all SMS through their SMSC so if you misconfigure your phone you will still get to send SMS (and so you can't use an external SMSC to send SMS without paying your telco...)
- lxgr 5y agoInteresting! Would that override still work when roaming internationally, though? It sounds similar to some providers implementing a "catchall" APN for data connections, which however has a habit of failing when roaming in my experience.