For those who have a Huawei HG8240 as the ONT, the default (Admin and User) Usernames and Passwords are
Admin:
    User: telecomadmin
    Password: admintelecom
User:
    User: root
    Password: admin
Local IP: 192.168.100.1

As I'm with Enable, we have the Huawei HG8240 and I have managed to get the SIP VOIP settings for MyRepublic

Server: sip.myrepublic.co.nz
Port: 5060
VLAN: 13
Registration Period: 3600

Dial Plan:
111|911|999|00xxxxx.T|001xxxxxxxxxx|0061[02-9]xxxxxxxx|01xxx.T|01[08]|0110|0133|0141xx|015[013-9]|01681800xxxxxxx|017[0239]|019[67]|0198xx|02xxxxxxxx.T|020[1278]xxxxxx|0210[03-7]xxxxx|021[12]xxxxxx|021[3-9]xxxxx|022xxxxxxx|026[02-9]xxxxxx|027xxxxxxx|028[037]xxxxxx|029xxxxxxx|0[3469]xxxxxxx|07xxxxxxxx.T|070[03]xxxxxx|07[2-9]xxxxxx|05xxxxx.T|0508xxxxxx|08xxxxx.T|0800xxxxxx|0830xx|08321x|0840[16]xxx|08405xx|087[459]x|1xxx.T|12[0-8]|129x|17[459]x|19[67]|19[34589]x|[2-9]xxxxxx|505|[*#]xx.T

Register User Name: 64Xxxxxxxx       
Auth User Name: 64Xxxxxxxx                    (Xxxxxxxx = your area code and phone number without the 0 in the area code)


The Password appears as asterisks, but using a Program "BulletsPassview" from Nirsoft.
I removed the asterisks and revealed the password


If you log in as the admin you should be able to remove / change the settings to stop it from registering to the server and set up your own device to register instead