Hello. we installed 2 intercoms that have a mini server and every button has a sip (3 buttons in total). we added those sips username and password and put an extension from the 3cx. the thing is sometimes is works sometimes it dosent (rings the extension), the intercom dials but sometimes the extension dosent ring and sometimes we just see a missed call the intercoms are Came bpt -Xpi/Eti. any idea's ?