HyperTerminal modem test

This page provides a step-by-step guide on how to check the status of an LTE SMS modem using AT commands. The examples were created using a Sierra Wireless EM7455 modem on the One Hungary LTE network.

Download: hyperterminal.zip

Preparation

To test the modem, connect it to the computer, then open the appropriate serial port in HyperTerminal or another terminal program. Press Enter after each command.

Recommended serial port settings

Setting	Value
Port	The modem's COM / ttyUSB port
Speed	115200 baud
Data bits	8
Parity	None
Stop bits	1
Flow control	None or hardware

An OK response means that the modem accepted and successfully executed the command.

1. Basic communication

AT

AT
OK

What it does: AT is the simplest attention command. It checks whether the modem responds on the serial port.

Result: OK indicates that basic communication between the computer and the modem is working.

2. Detailed error messages

AT+CMEE=2

AT+CMEE=2
OK

What it does: enables detailed error codes. A failed command will then return not only ERROR but also a more precise +CME ERROR code.

Result: detailed error reporting has been enabled. This is especially useful for troubleshooting.

3. SIM card status

AT+CPIN?

AT+CPIN?
+CPIN: READY

OK

What it does: queries the PIN status of the SIM card.

Result: +CPIN: READY means that the SIM has been detected, no PIN is required, and the modem can use it.

If SIM PIN, SIM PUK, or ERROR appears here, SMS sending and network registration may also be problematic.

4. SIM identifier

AT+CCID

AT+CCID
+CCID: 89367031562539221530

OK

What it does: displays the SIM card's unique ICCID identifier.

Result: 89367031562539221530 is the SIM's physical identifier. The 893670 prefix indicates Hungary and the Vodafone network.

5. IMSI identifier

AT+CIMI

AT+CIMI
216703132537153

OK

What it does: queries the SIM's IMSI identifier.

Result: the IMSI is the international identifier of the mobile subscription. 216 indicates Hungary, and 70 is the mobile network code for Vodafone Hungary.

6. SMS storage

AT+CPMS?

AT+CPMS?
+CPMS: "SM",0,20,"SM",0,20,"SM",0,20

OK

What it does: queries the storage locations for SMS messages and the available capacity.

Result: all three storages are "SM", meaning they are on the SIM card. "SM",0,20 means that 0 messages are currently stored and there is room for a total of 20 messages.

7. Network registration

AT+CREG?

AT+CREG?
+CREG: 0,1

OK

What it does: queries whether the modem is registered on the mobile carrier's network.

Value	Meaning
`0`	Reporting of automatic registration events is disabled.
`1`	The modem is registered on its own home network.

Result: +CREG: 0,1 means that the modem has successfully registered on its home network.

8. Current provider

AT+COPS?

AT+COPS?
+COPS: 0,0,"One HU",7

OK

What it does: shows which mobile network the modem is currently connected to.

Value	Meaning
`0`	Automatic network selection.
`0`	The provider name is shown in long alphanumeric format.
`"One HU"`	The name of the current network: One Hungary.
`7`	The technology in use: LTE / 4G.

9. Available networks

AT+COPS=?

AT+COPS=?
+COPS: (2,"One HU","One HU","21670",7),
(1,"216 04","216 04","21604",7),
(1,"Telekom HU","THU","21630",7),
(1,"Telenor HU","TelenorH","21601",7),
,(0,1,2,3,4),(0,1,2)

OK

What it does: lists the mobile networks that the modem detects at its current location.

Network	MCCMNC	Status
One HU	21670	`2` – currently selected network
216 04	21604	`1` – available
Telekom HU	21630	`1` – available
Telenor HU	21601	`1` – available

21670 is the network code for One Hungary, and 7 indicates LTE technology.

10. Signal strength

AT+CSQ

AT+CSQ
+CSQ: 28,99

OK

What it does: queries the received radio signal strength and the bit error rate.

Value	Meaning
`28`	Strong signal; on a scale of 0–31, 28 is close to the maximum.
`99`	The bit error rate cannot currently be measured, which is common under normal conditions.

28 corresponds to a received level of approximately -61 dBm, which is considered good, stable LTE reception.

11. Firmware and model

AT+CGMR

AT+CGMR
SWI9X30C_02.38.00.00 rE3F3E55C03AE94 jenkins 2022/01/13 05:16:00

OK

What it does: displays the modem's firmware version.

Result: the modem uses SWI9X30C_02.38.00.00 firmware.

AT+CGMM

AT+CGMM
EM7455

OK

What it does: queries the modem's model number.

Result: the modem is a Sierra Wireless EM7455 LTE module.

12. Detailed modem status

AT!GSTATUS?

AT!GSTATUS?
!GSTATUS:
Current Time:  111              Temperature: 29
Reset Counter: 1                Mode:        ONLINE
System mode:   LTE              PS state:    Attached
LTE band:      B1               LTE bw:      20 MHz
LTE Rx chan:   500              LTE Tx chan: 18500
LTE CA state:  NOT ASSIGNED
EMM state:     Registered       Normal Service
RRC state:     RRC Idle
IMS reg state: No Srv

PCC RxM RSSI:  -60              RSRP (dBm):  -93
PCC RxD RSSI:  -66              RSRP (dBm):  -99
Tx Power:      --               TAC:         14CD (5325)
RSRQ (dB):     -12.6            Cell ID:     0013B628 (1291816)
SINR (dB):      6.6

OK

What it does: the Sierra Wireless AT!GSTATUS? command shows the modem's detailed operating status.

Field	Value	Meaning
Temperature	29	The modem temperature is 29 °C, normal.
Mode	ONLINE	The modem is active and running.
System mode	LTE	The modem is on an LTE/4G network.
PS state	Attached	The modem is attached to the packet-switched data network.
LTE band	B1	Band 1, an LTE band around 2100 MHz.
LTE bw	20 MHz	It uses a 20 MHz wide LTE channel.
EMM state	Registered, Normal Service	Successful registration, normal service.
RRC state	RRC Idle	The modem is registered but currently has no active data transfer.
IMS reg state	No Srv	The IMS/VoLTE service is not active; this is not necessarily required for SMS and LTE data connections.
RSRP	-93 dBm	Good LTE signal strength.
RSRQ	-12.6 dB	Acceptable, medium-good signal quality.
SINR	6.6 dB	Adequate signal-to-noise ratio; not excellent, but usable.

Registered and Normal Service together mean that the modem is properly registered and usable. RRC Idle is not an error: it only indicates that there is no continuous data traffic at that moment.

Summary of results

Area	Result
Serial communication	Working
SIM card	Detected, usable without a PIN
SIM identifiers	ICCID and IMSI readable
SMS storage	On the SIM, with a 20-message capacity
Network registration	Successful, on the home network
Provider	One Hungary
Technology	LTE / 4G
Signal strength	Strong
Modem status	Online, registered, normal service

This output indicates that the modem is ready for SMS sending and network communication.

Common troubleshooting

Symptom	Likely cause	Action
No response to the `AT` command	Wrong port, cable, driver, or baud rate	Check the port and cable, set 115200 baud
`AT+CPIN?` → `ERROR`	The modem cannot see the SIM, or a PIN/PUK is required	Reinsert the SIM, check the PIN status
`AT+CCID` → `ERROR`	SIM socket, SIM contacts, or modem fault	Test another SIM and modem
`+CREG: 0,0`	No network registration	Check the antenna, SIM activity, and `AT+COPS=?`
`+CSQ: 0,99` or a low value	Weak signal or antenna problem	Check the antenna connection and placement