I've just made an appointment to have someone call me on my landline, but after the call starts, it may be desireable to include another party on the call.
Since this isn't a regular need, rather than pay for a monthly service to allow this, or set up a conference call, I'll probably call the third
party on my cellphone.
What I'd like is an easy means to connect the two calls so that all 3 of us could talk.
(I will probably kludge something together involving a couple of transformers and capacitors, an RJ-11 connector and that peculiar 4-contact 2.3mm phone plug used by cellphones.)