Manufacturer: http://www.myungmin.com/solution/pro_indoor_cpe_2.php
Reseller: https://parduotuve.mezon.lt/prekes?act=product&id=45

Why I don't like locked by reseller SIP devices? I don't know :)
LOL

Do It At Your Own Risk:

Let's play.
1) login to box
http://ipaddress
defaultlogin:admin
defaultpass:admin

(Password not correct? Reset button can help You)

SIP config can be found in "hidden" place:

http://ipaddress/cgi-bin/sipaccount.html
Server Mode: Proxy / Disable proxy / OutBound

SIP Proxy
Address: sip.provider.com Port No. (1 ~ 65535)

SIP Registrar
Address: sip.provider.com Port No. (1 ~ 65536)
Expires (30 ~ 36000)

Phone List
Phone Port: 1/2
Phone Num:
Display Num:
Auth ID:
Auth Passwd:
Codec: PCMA/PCMU/G729/G723
DTMF: RFC2833/Inband/Outband

More interesing links:
http://ipaddress/cgi-bin/sipphonelist.html

Phone Port No: 1/2
User Name:
Display Name:
Codec: PCMA/PCMU/G729
Packetization Period: 20-XX(ms)
DTMF RFC2833/Inband/Outband

http://ipaddress/cgi-bin/siphostconfig.html

Interface wb0/eth0
Port No. 5060
Transport: TCP/UDP
Use Proxy: Yes/No
Prack: Enable/Disable

Current SIP Authenitcation: http://ipaddress/cgi-bin/sipauthenticationlist.html
DSP settings: http://ipadress/cgi-bin/dspfeature.html

Enjoy!

PS
If You dont have REBOOT button in Your web interface (SystemSetup/WebEnvironmentSetup/CPEReboot) login to box by telnet (with web password) and type word "enable" (without "), press ENTER and confirm by password. Now You can rebooot this device from web interface.