Thanks, but its on a 5A variable psu at 4.00v
Now seen some posts suggesting the problem may be in the AT+CBAND default settings, so just trying a variation on them.....
Edit,
Have compared the settings of the older working Sim800L with the new one and have got the CBAND as EGSM_MODE,ALL_BAND and the COPS shows "02" .
Have also tried changing to all of the different CBAND modes, this does affect the flashing, some settings a few flashes lower, other setting it flashes all the time, but seems it does not want to log on.
The Sim card is in the right way around , the 4v linear psu is good, the Arduino lines are correctly resistored exactly the same as the working old Sim800L, but something still not right ??