Our office has the RCA 25423RE1 phone system. How do I access voicemail remotely?

SOURCE: how to check voicemail

THROW IT AWAY-- HAVE 3 AND ALL ARE JUNK. THERE IS A DIFFERENT PROBLEM EVERYDAY. NEVER WORKED PROPERLY SINCE DAY ONE . TOOK BACK TO STAPLES AND GOT NEW ONES AND THEY ARE NO BETTER

SOURCE: Jack requirements

You can use a standard RJ-14 two line jack. This type of has a minimum of 4 wires inside the jack. You can also use a 6 wire jack, but not a 8 wire jack.