I have 22 calling modems and 500 waiting for calls. (wavecom fastrack supreme)
When I start one call (or two) everything is OK, it connects without a problem
But when i start 7 or 8 calls in the same time, most of calls respond “NO CARRIER”. GSM company says that the signal is strong enough.
After “NO CARRIER” reply, “AT+CEER” command replies error number 47(sometimes 127).