Hi Colin,
Maybe better to start a new thread so your question can get better exposure, you can link to this old thread for history.
However, according to below,
I believe your observation is vendor/product specific behavior, for SL809x/SL808x (non-T), after we sent ATD*99 to modem, it will respond with “CONNECT” and wait for PPP frame from host.
In most popular dialup tool, e.g. windows dialup, linux PPP, both behavior will works.
Are you working on your proprietary dialer? can you start the PPP session by sending PPP frame on receiving “Connect” from module?
Thx
L