Arrangements for transferring received calls from one subscriber to another; Arrangements affording interim conversations between either the calling or the called party and a third party (substation line holding circuits H04M1/80)

Full Title

Automatic or semi-automatic exchanges > Systems providing special services or facilities to subscribers (specially adapted for wireless communication networks H04W4/00) > Arrangements for transferring received calls from one subscriber to another; Arrangements affording interim conversations between either the calling or the called party and a third party (substation line holding circuits H04M1/80)