Strange you should post this! I was going to start using it to replace the Linux Skype client (the old 4.3, which has now been retired from service), and had it all installed and sym-linked into my Pups from a remote partition I share a lot of data from, when I came across something even better...
I've been using this to chat with a friend down in the south-eastern corner of Louisiana for the last few months. She's on an iPhone, and normally uses Skype. However, since Skype's always been a bit 'problematic' in Puppy (mainly due to M$'s insistence on using PulseAudio, which is not standard fare for the Pups), she agreed to give WIRE a try. It's cross-platform, and the Linux implementation is an AppImage.....a totally self-contained executable binary package, which you can run from anywhere you like.
Visit the link, click 'Get App' at the top. On the next page, scroll down to 'Linux'; click on the drop-down, and select from 'AppImage (32-bit)' or 'AppImage (64-bit)'.
If Telegram's anything like this one, then yes; you will need both parties to have it installed. Like Skype; M$ will not let Skype connect to anything other than another Skype client. I've yet to find VoiP apps that will cross-connect; WIRE is, I'm afraid, no different.
I suspect Telegram is the same.
WIRE, I've used for text chatting so far. My friend, Ally, is hard to pin down, and I may not hear from her for weeks, sometimes months at a time. We haven't yet tried the video calling capabilities. Pretty soon, I shall sweet-talk my sister ( a mere 70 miles away!) into installing this, and giving it a try.....just so's I can find out what it's like.
Distros:- Multiple 'Puppies'..... and Anti-X 16.1
My Puppy BLOG ~~~ My Puppy PACKAGES
Compaq Presario SR1916UK; Athlon64 X2 3800+, 3 GB RAM, WD 500GB Caviar 'Blue', 32GB Kingspec PATA SSD, 3 TB Seagate 'Expansion' external HDD, ATI Radeon Xpress 200 graphics, Dell 15.1" pNp monitor (1024 x 768), TP-Link PCI-e USB 3.0 card, Logitech c920 HD Pro webcam, self-powered 7-port USB 2.0 hub
Dell Inspiron 1100; 2.6 GHz 400FSB P4, 1.5 GB RAM, 64GB KingSpec IDE SSD, Intel 'Extreme' graphics, 1 TB Seagate 'Expansion' external HDD, M$ HD-3000 'Lifecam'.