A6 GSM Modemmit Nano - SMS Senden

also die Kommunikation klappt meistens.

So gebe ichs im serial Monitor aus:
SETUP: SoftwareSerial.begin()
SETUP: SoftwareSerial.listen()
******************************** START **************************************
SND> AT&F

AT&F
<>
<>OK
< => Startup response OK
******************************** SEND NOW **************************************
SND> AT+CMGF=1
0 Got response from AT [10ms]: AT+CMGF=1

0 Got response from AT [10ms]:

0 Got response from AT [10ms]: OK

SND> AT+CMGS="
1 Got response from AT [10ms] - Send Number: AT+CMGS="0676834!??!?"

1 Got response from AT [10ms] - Send Number:

1 Got response from AT [10ms] - Send Number: >
SND> "ctrl+z
2 Got response from AT[10ms]: Test

2 Got response from AT[10ms]:

2 Got response from AT[10ms]: +CMS ERROR:500


+CMS ERROR:500 scheint das Problem zu sein. Die Sim hat jedoch Guthaben und ist entsperrt.
Der Empfang war gestern gut, heute jedoch klappts nicht mehr