I'm using the cape model: VAYU2-4GEC25-E (https://www.yantrr.com/product/vayu2-4g-ltecat4asia-eu-w-gps/) together with a Beaglebone Enhanced that running on Debian 9.5 2018-10-07 4GB eMMC IoT .
I started ppp connection as described below with wvdial: