old people,like me, still hate those things. 4 wire e&m is most common, and a you know they have 6 wire, with a test set on xmit and rec. a ground on the e lead should give you dial tone from the far end. a ground on the m lead should give you dial tone from your switch. make sure you have your route programed to return dt., if that is what the other end needs. you can wire 2 back to back like the 1st reply said, and that will prove to you, that your software/hardware is right. but it will not prove it to the distant switch. Type B e&m used SF (signal Freq) instead of ground. Haven't seen either in years..
john poole
bellsouth business
columbia,sc