def _inc_decode(idec):
        decoded=list()
        # define so we KNOW we hit a mark as last char
        hop=gsm_alpha_gsm.index('\x1b')+1
        final=False
        for i in range(0,len(gsm_alpha_gsm),hop):
            end=i+hop
            if end>=len(gsm_alpha_gsm): final=True
            decoded.append(idec.decode(gsm_alpha_gsm[i:end],final))
        return ''.join(decoded)