graph G {
    pstn -- twilio;
    other_hams -- hh;
    allstar -- hh;
    twilio -- pbx;
    hh -- pbx;
    pbx -- phone, desktop, laptop;
    
    pstn[label="PSTN"];
    twilio[label="Twilio"];
    other_hams[label="Other Hams"];
    allstar[label="AllStarLink"];
    hh[label="Hamshack Hotline"];
    pbx[label="My PBX"];
    phone[label="My Phone"];
    desktop[label="My Desktop"];
    laptop[label="My Laptop"];
}