The adapters are intended to be used for calls coming into {HEAD ~ a PBX} on a DID trunk or {TAIL ~ E&M tie line} 
The adapters are intended to be used for calls coming into { HEAD ~ a PBX } on a DID trunk or { TAIL ~ E&M tie line }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL