Two things

[obnoxiousish]

First one, I send an SMS to a using certain canadian carrier with the normal sendSms function, it delivers BUT if I try another it fails CMS or CME or GSM error 21 sms rejected / invalid index

However another carrier if I try lots of sendSms it works fine without error

Can only get the first one to work by completely reconnecting and sending again
Considering it works once then breaks I feel like something is wrong with what commands the device is expecting or the carrier is expecting? Not sure any ideas

Secondly, should add

    @property
    def iccid(self):
        """ :return: The modem's ICCID number """
        return self.write('AT+QCCID')[0]