EG915U-EU Voice Call Support in LTE mode

IoT Modules LTE Standard Module
1

Hi,

I see a problem with incoming Voice Call support in EG915U-EU module.
When the module is in GSM network, an incoming voice call results in +CRING, +CLIP notifications as it should be:
18:42:49.807, +QCSQ: “GSM”,-106
++incoming call initiated here++
18:42:56.928, +CRING: VOICE
18:42:56.928,
18:42:56.990, +CLIP: “xxxxxxxxx”,145,0,0
18:42:56.990, ATH0
18:42:57.490,
18:42:57.490, OK

But in LTE mode, no such notifications are visible, and only fallback to GSM mode (for 3 seconds) is notified:

18:40:45.679, +QCSQ: “LTE”,95,-128,39,-15 ← operating in LTE
…
++incoming call initiated here++
18:40:55.619, +CREG: 2,1,“0071”,“014E934”,7
18:40:55.931, +CREG: 1,“0583”,“4044”,0 ← fallback to GSM for unknown reason
…
18:40:56.054, +QCSQ: “GSM”,-0
…
18:40:58.429, +CREG: 1,“0071”,“014E952”,7 ← back to LTE mode for unknown reason
…
18:41:06.368, +QCSQ: “LTE”,91,-120,52,-12 ← operating in LTE again

During this attempt, the initiating side of a call hears the message: “the number you’re calling is unavailable at the moment” as if the LTE module was switched off.

  1. Does this module support VOLTE ? Voice calls in LTE should be handled in this way, as far as I’m concerned.

  2. Why there is absolutely no incomming call notification present when operating in LTE mode?

The firmware version of this module is: EG915UEUABR02A04M08 .

A response to AT+QCFG:
18:38:22.913, AT+QCFG=?
18:38:22.913,
18:38:22.913, +QCFG: “nwscanmode”,(0,1,3),(0,1)
18:38:22.976, +QCFG: “band”,(0-FFFF),(0-7FFFFFFFFFFFFFFF),(0,1)
18:38:23.038, +QCFG: “creg/emergency”,(0,1)
18:38:23.038, +QCFG: “pdp/retrytimes”,(0-10)
18:38:23.103, +QCFG: “airplanecontrol”,(0,1)
18:38:23.103, +QCFG: “qcsq/rssi/negative”,(0,1)
18:38:23.162, +QCFG: “usbnet”,(1,3)
18:38:23.162, +QCFG: “nat/cid”,(0-FFFFFFFF)
18:38:23.226, +QCFG: “urc/ri/smsincoming”,(“off”,“pulse”),(5-2000),(1-5)
18:38:23.287, +QCFG: “urc/ri/other”,(“off”,“pulse”),(5-2000),(1-5)
18:38:23.350, +QCFG: “urc/ri/ring”,(“off”,“pulse”),(5-2000),(1-5)
18:38:23.350, +QCFG: “urc/delay”,(0-120)
18:38:23.415, +QCFG: “urc/cache”,(0,1)
18:38:23.475, +QCFG: “risignaltype”,(“respective”,“physical”)
18:38:23.475, +QCFG: “cmux/urcport”,(0-4)
18:38:23.542, +QCFG: “fota/cid”,(1-7)
18:38:23.542, +QCFG: “fota/times”,(0-120)
18:38:23.542, +QCFG: “fota/path”,
18:38:23.602, +QCFG: “pkalive/ip”,(1-2),<IP_address>,(0-65535)
18:38:23.665, +QCFG: “ledmode”,(0,1)
18:38:23.665, +QCFG: “led/sim”,(0,1)
18:38:23.725, +QCFG: “tone/incoming”,(0,2,3)
18:38:23.725, +QCFG: “ntp”,(1-10),(5-60)
18:38:23.725,
18:38:23.725, OK

Response to QCFG=ims (should turn on VOLTE, according to other posts: Does my EG915U module support VoLTE? ):
18:39:50.037, AT+QCFG=“ims”
18:39:50.037,
18:39:50.100, +CME ERROR: 3

Regards,
Pablo

2

hi,
The version supports volte. Please use the following command to open volte and test it.
at+qims=?
at+qims=“enable”
thanks

3

Hello,
Thank you for a professional response.
The command “AT+QIMS” helped a lot.
Now the module receives +CLIP, +CRING messages during incomming voice call in LTE mode, as it should. This problem seems to be solved.

Is there any newer version of the Firmware for EG915U-EU?
I still see some minor bugs in this Firmware during execution of certain AT commands related to network services.
The firmware version of the purchased modules is: EG915UEUABR02A04M08.

Best Regards,
Pablo

4

hi,

You’re welcome, please check your email. A new firmware version was sent.

thanks.

5

Hello,

Thank you for the new version of the firmware,
Where can I find any manual or application note that explains firmware procedure step by step ?

Best regards!

6

Hi,

We also use the EG915U-EU. I realize it might be a long shot, but I’m wondering if there’s an AT command that can automatically configure a SIM card for VoLTE. Currently, to enable VoLTE, we have to manually insert each of the 300 SIM cards we use monthly into a cellphone. This step is necessary before these SIMs can work for calling when placed in the module.

Regards,
Claud

7

Hi Claud,

Actually I managed to turn on VoLTE in EG915E-EU by this single (but undocumented) AT command:

During tests in 4G, this command solved our problem. The module now shows +CRING, +CLIP notifications during incomming call from LTE network, without any fallback to 2G.

Perhaps some VoLTE initiation was also necessary by ougoing voice call initiation from the module (ATD tel_number;) - but I didn’t confirm it yet. I also didn’t test audio transmission (not used in my application).

Regards,
Pablo