3 ms·

Don't lots of phones still send SMS & voice calls over GSM/CDMA? I know VoLTE is appearing, but slowly & only on a couple flagship devices, and quality degrades

• joecool1029 10y ago
  Haven't actually seen the signal degradation issues you speak of, probably offset by being able to use a lower band than GSM or HSPA for my carrier. Carriers have made it a policy to not whitelist imported devices for voLTE. IMEI needs to be whitelisted at carrier AND carrier file installed in phone needs to have support turned on. Either thing missing, no voLTE for you. EDIT: Forgot to mention, non-voLTE still signals with LTE for incoming calls and SMS, it'll handover to HSPA/CDMA/GSM within about 2 seconds of the signal coming in. Unfortunately I don't have specifics of this process.
  • deleted 10y ago
    [deleted]
• digi_owl 10y ago
  Actually i think most SMS is handled via "WAP" these days, meaning that it is carried as a short duration data connection rather than as a special packet in the cells control channel (GSM, dunno about how CDMA implemented it).
  • joecool1029 10y ago
    the GPRS setting is blocked on featurephones. Still opts for CSD sending there. Newer devices send over 'IMS' (which is voLTE, and also part of HSPA+) It was a funny loophole to get unlimited SMS on T-Mobile back when they just changed name from Voicestream.
    • digi_owl 10y ago
      I guess it depends on where in the world one lives. I'm not American, and thus my phone is free of carrier tampering. I even learned about the SMS over GPRS (thanks) thing because a relative of mine once owned a phone where we had to turn it off to actually get reliable SMS delivery, as it defaulted to GPRS mode.