Replacing a 2.5G Optical Modem on Beijing Unicom

Preface

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In January 2022, I bought a 2.5G soft router with a J4125 processor on Xianyu (second-hand marketplace), which kicked off my journey of tinkering with networking gear. In February, PON sticks became popular, and I originally planned to buy one to replace my home optical modem. But I heard they ran quite hot and would drop connections when overheated, so I dropped the idea.

In the second half of 2024, ZTE’s F7015tv3/F7005tv3 suddenly gained popularity. They have very low power consumption¹, come with one 2.5G Ethernet port, one IPTV port, and two Gigabit Ethernet ports. The difference between the two models is that the F7015tv3 has an additional phone port. Since my broadband plan includes a landline (even though I barely get any calls), I ended up buying the F7015tv3 on Xianyu. When it arrived, I was surprised by how compact it is, about the same length as my iPhone 13 mini.

Hardware Info

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# cat /proc/capability/boardinfo
system:LINUX
cpufac:ZXIC
cpumod:ZX279133
2gwlmod:MTK
5gwlmod:MTK
cpufre:1000MHZ
cpunum:2
flshcap:256MB
ddrcap:512MB

Preparation

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Open the old modem’s web interface and log in with the super admin account. Here’s the login method for Beijing Unicom: open 192.168.1.1, press F12, and enter the following in the Console.

document.getElementById("loginfrm").setAttribute("method", "get");
document.getElementById("username").value = "CUAdmin";
document.getElementById("password").value = "CUAdmin";
document.getElementById("loginfrm").submit();
submitFrm();

Record the SN/MAC address, device number, and connection configuration VLAN information (take screenshots or photos for reference).

Configuring the New Modem ²

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• Log in to the new modem’s web interface using the super account useradmin with password nE7jA%5m. Go to Management → Uplink Mode, and switch to XGPON or XEPON depending on your broadband type.

• Enable the modem’s Telnet³. Change your computer’s network card MAC address to 000729553357, then run the following command. When prompted to reboot, wait for the modem to restart automatically.

zteOnu --telnet

• Delete existing network configurations:

sendcmd 1 DB p WANC
sendcmd 1 DB delr WANC 0
sendcmd 1 DB delr WANC 1

Delete as many entries as there are by changing the number after WANC.

• Create a new network connection following the configuration from the old modem.

• Use Telnet to modify modem parameters. Run setmac show2 to view system parameters.

Change Region

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# cat /etc/init.d/regioncode
200:Jiangsu
201:Xinjiang
202:Hainan
203:Tianjin
204:Anhui
205:Shanghai
206:Chongqing
207:Beijing
208:Sichuan
209:Shandong
210:Guangdong
211:Hubei
212:Fujian
214:Zhejiang
215:Shanxi
216:Hunan
217:Yunnan
218:Xizang
219:Heilongjiang
220:Guizhou
221:Shanxi2
222:Hebei
223:Ningxia
224:Guangxi
225:Jiangxi
226:Gansu
227:Qinghai
229:Liaoning
230:Jilin
231:Neimeng
232:Henan
234:TelecomInstitute

# Switch to Beijing region
upgradetest sdefconf 207

Change MAC Address

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setmac 1 32769 12:34:56:78:90:12

Change Device Code (First 6 Digits)

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setmac 1 768 xxxxxx

Change Device Code (Last 17 Digits)

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setmac 1 512 xxxxxxxxxx

ITMS Spoofing

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sendcmd 1 DB set PDTCTUSERINFO 0 Status 0
sendcmd 1 DB set PDTCTUSERINFO 0 Result 1
sendcmd 1 DB save

Once all modifications are complete, connect the fiber optic cable and restart.