WP76xx - FW - serial USB or UART - ATDT*99***2# or AT+CGACT fail to start or use a new context

For serial USB or UART connections ATDT99**2# or AT+CGACT fail to start or use a new context

This is a follow up to this forum topic that was closed by SW without resolution

Further investigation seems to indicate that it is not possible to activate a context via the serial port with the current WP76xx firmware What happens is that the automatic context 1 is always reused.

However if the modules Linux / legato command line tool cm is used it is possible to activate alternative contexts.

Why does this matter? What if the SIM in use is roaming onto the host network. From practical testing it appears that using a context other than context 1 (auto connected to real host network) works around connectivity issues.

This link is to a report on my testing so far.

The following methods have been investigated

  1. WP Linux Legato app command line tool cm
  2. Manual serial AT command line interface including AT+CGACT
  3. PPP serial using a combination of chat AT commands and pppd

The link also contains the Qualcomm DM log files and details on the testing carried out - where useful the Qualcomm DM log has been decoded.

As can be seen when Legato cm is used the modem starts a new context - in all other cases the modem does not start a new context.