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Cellular connection process
Connecting
In normal operations, the XBee Smart Modem automatically attempts both a cellular network
connection and a data network connection on power-up. The sequence of these connections is as
follows:
Cellular network
1. The device powers on.
2. It looks for cellular towers.
3. It chooses a candidate tower with the strongest signal.
4. It negotiates a connection.
5. It completes cellular registration.
Data network connection
1. The network enables the evolved packet system (EPS) bearer with an access point name
(APN). See
2. The device negotiates a data connection with the access point.
3. The device receives its IP configuration and address.
4. The
AI (Association Indication)
Data communication with remote servers (TCP/UDP)
Once the data network connection is established, communication with remote servers can be
initiated in several ways.
Note
For NB-IoT, TCP support is dependent on the network. Contact your network provider for
details.
Transparent mode data sent to the serial port (see
n
Timeout)
for timing).
API mode:
n
Digi Remote Manager connectivity begins.
n
Data communication begins when:
1. A socket opens to the remote server.
2. Data is sent.
Data connectivity ends when:
1. The server closes the connection.
2. The TM timeout expires (see
3. The cellular network may also close the connection after a timeout set by the network
operator.
Digi XBee® 3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
AN (Access Point Name)
if you have APN issues.
command now returns a 0 and the sockets become available.
Transmit (TX) Request: IPv4 - 0x20
TM (IP Client Connection
TD (Text Delimiter)
and
received over the serial connection.
Timeout)).
Connecting
RO (Packetization
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Troubleshooting
