You could have with two 9V batteries https://electronics.stackexchange.com/questions/548222/providing-phone-line-current-for-direct-modem-modem-communication ht

You could have with two 9V batteries https://electronics.stackexchange.com/questions/548222/providing-phone-line-current-for-direct-modem-modem-communication https://electronics.stackexchange.com/questions/548222/provi...