WeeChat[0] (or any IRC client, really, but weechat is nice) with Bitlbee[1] supports a metric assload of services, albeit by pretending they're IRC (which does work - I spent years in weechat/irssi with bitlbee talking to various people on disparate services.)

Or if you're just after Telegram/WhatsApp, nchat[2] is ok (I can vouch for the Telegram half only.)

[0] https://weechat.org

[1] https://wiki.bitlbee.org

[2] https://github.com/d99kris/nchat