Sim900找不到网络

Question

我有一份来自圣斯马特的Sim900。我有一个工作的串行连接从我的覆盆子Pi到Sim900。我可以编写命令、接收响应，甚至可以从Sim卡查询诸如我的电话号码等数据。我的Sim卡是AT&T卡。我无法让Sim900找到一个网络并尝试连接。据说，它应该自己动手，但我也没见过。我唯一能想到的两件事是，要么固件出错，要么芯片没有足够的电源。固件(来自AT+CGMR)是Revision:1137B06SIM900M64_ST_ENHANCE。这似乎是您可以从Simcom站点获得的最新固件。至于电源，我很肯定，因为我买了一个充电器usb电缆和适配器，其中适配器随电缆承诺支持2安培。我剥掉了电缆，给了它3安培的电源。当我尝试连接芯片时，芯片也不会随机重置。我可以设置在断电时丢失的设置，但只有当我拔掉芯片以重置设置时，它们才会消失。

下面的输出来自我最近的测试，试图理解为什么我不能发送短信。

----------------------------------------------------------------------------------------
Command: "b'AT\r\n\r\n'" Response: "AT


OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CMEE=2\r\n'" Response: "AT+CMEE=2

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CFUN?\r\n'" Response: "AT+CFUN?

+CFUN: 1

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CREG=2\r\n'" Response: "AT+CREG=2

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CREG?\r\n'" Response: "AT+CREG?

+CREG: 2,0

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+COPS?\r\n'" Response: "AT+COPS?

+COPS: 0

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+QBAND?\r\n'" Response: "AT+QBAND?

ERROR
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CSQ\r\n'" Response: "AT+CSQ

+CSQ: 20,0

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+QENG?\r\n'" Response: "AT+QENG?

ERROR
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CIMI\r\n'" Response: "AT+CIMI

310REDACTED

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CNUM\r\n'" Response: "AT+CNUM

+CNUM: "","1678REDACTED",129,7,4

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CMGF=1\r\n'" Response: "AT+CMGF=1

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CSCS=?\r\n'" Response: "AT+CSCS=?

+CSCS: ("IRA","GSM","UCS2","HEX","PCCP","PCDN","8859-1")

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CSCS="GSM"\r\n'" Response: "AT+CSCS="GSM"

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CREG?\r\n'" Response: "AT+CREG?

+CREG: 2,0

OK
"
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'AT+CMGS="978REDACTED"\r'" Response: "AT+CMGS="978REDACTED"

> "
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
Command: "b'Pi\x1a'" Response: "Pi
+CMS ERROR: operation not allowed
"
----------------------------------------------------------------------------------------

生成此输出的Python3脚本如下所示：

import serial
import time
import binascii

ser = serial.Serial(port='/dev/serial0',baudrate=9600,timeout=1)

command = bytes("AT" + '\r\n', 'utf-8') + binascii.a2b_hex('0D0A')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CMEE=2'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

#ser.write(bytes("ATE0" + '\r\n', 'utf-8')) # Reverse it with ATE
#rcv = ser.read(1000)
#print(rcv)
#time.sleep(1)

command = bytes('AT+CFUN?'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CREG=2'+'\r\n', 'utf-8') # What does 2 do?
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CREG?'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

#command = bytes('AT+COPS=?'+'\r\n', 'utf-8')
#ser.write(command)
#rcv = ser.read(1000)
#print("----------------------------------------------------------------------------------------")
#print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
#print("----------------------------------------------------------------------------------------")
#time.sleep(10)

command = bytes('AT+COPS?'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

#ser.write(bytes('AT+COPS=0'+'\r\n', 'utf-8'))
#rcv = ser.read(1000)
#print("\"%s\"" % rcv.decode())
#time.sleep(1)

command = bytes('AT+QBAND?'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CSQ'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+QENG?'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CIMI'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CNUM'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

#ser.write(bytes('AT+CNMI=2,1,0,0,0'+'\r\n', 'utf-8'))
#rcv = ser.read(1000)
#print(rcv)
#time.sleep(1)

# TEXTING

command = bytes('AT+CMGF=1'+'\r\n', 'utf-8') # Select Message format as Text mode 
ser.write(command) 
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CSCS=?'+'\r\n', 'utf-8') # Possible Value: GSM
ser.write(command) 
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CSCS="GSM"'+'\r\n', 'utf-8') # Possible Value: (8859-1/latin-1)
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CREG?'+'\r\n', 'utf-8')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(1)

command = bytes('AT+CMGS="978REDACTED"', 'utf-8') + binascii.a2b_hex('0D') # 0D is CR
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(5)

command = bytes("Pi",'utf-8') + binascii.a2b_hex('1A')
ser.write(command)
rcv = ser.read(1000)
print("----------------------------------------------------------------------------------------")
print("Command: \"%s\" Response: \"%s\"" % (command, rcv.decode()))
print("----------------------------------------------------------------------------------------")
time.sleep(5)

#ser.write(binascii.a2b_hex('0D0A')) # 0D is CR
#rcv = ser.read(1000)
#print("\"%s\"" % rcv.decode())

同样，在minicom中运行时也会出现同样的问题。这不是Python特有的问题。尽管显示AT命令"AT+COPS=?“中的数据存在问题？在Python里。然而，显示错误是另一天的问题，因为我仍然可以在minicom中阅读它。

编辑:澄清问题

基本上，我想知道为什么我不能发送短信，以及如何修复它！我确信这与没有在任何网络上注册有关，但是在运行"AT+COPS=?“时没有出现连接到的网络。列出任何潜在的原因将不胜感激。如果需要的话，我可以为我的设置拍照。

编辑:提供一些关于"AT+COPS=?“的见解。

使用Minicom，我可以得到"AT+COPS=?“的以下结果。我不能在Python 3中测试这个命令，因为它使来自自身的反馈和其他所有未来的命令都是空的，比如空引号(例如"")。即使启用了CMEE来提供详细的文本，也是一个问题。当我重置Python程序时，这会被重置。

AT+COPS=?
+COPS: (1,"Off Network","","310260"),,(0,1,4),(0,1,2)

OK

每次运行命令时都会得到上述结果，无论我将CREG设置为什么。

链接：我购买Sim900的亚马逊网页

Answer 1

事实证明，我的代码或硬件都没有问题。这是我的网络提供商AT&T的一个问题，现在，我知道他们已经摆脱了2G，但我没有意识到这也意味着电话和短信。因为我忘记了电话和短信不是单独的协议。因为，我在我的手机上输入这个，我只会用截图来显示我的意思。

这是一个网络子模式列表。我的手机通常是LTE数据的首选选项。我的GSM芯片使用的是第二种选择，显然是GSM。我可能能够破解一个较慢的LTE连接，因为我仍然支持的乐队，AT&T的LTE网络提供。我只需要看看破解固件是多么的可行。

​

​

这就是我的LTE网络列表在扫描时的样子(本质上是AT+COPS=?)：

​

​

这是我的GSM芯片看到的相同的输出。这是GSM的选项。当选择关闭网络选项时，我不能打电话给任何人。

​

​

考虑到这一点，我要么需要找到一家支持GSM的运营商，要么将固件合并起来支持慢LTE，要么砍掉我的手臂，在黑市上卖给一个昂贵的LTE芯片。