Telephony
Growing up in the 80's and 90's I've used rotary phones and explored phone trees, actually war dialed large swaths of phone numbers looking for interesting systems and in the waning years used BBS's before they died.
I've restored several vintage payphones from the 80s and 90s and added VoIP capability to them via Asterisk PBX. I also developed a system to ring my cellphone when traveling internationally and provide me with a dial tone to call out back when international travel plans were very expensive but inbound calls were free from local numbers. Using one's skills to create custom services to solve problems is a skill I'm glad to have and continue to develop.
incoming: projects