This is a simpler method of upload bonding than others, where you just want to round robin packets to the upstream, which is the normal case for AAISP.
You may wish to add ppp3, etc. as pppd sometimes allocates a different number overriding the unit directive. There's no harm in having too many.
In /etc/ppp/ip-up.d place the following script:
#!/bin/sh sysctl -w net.ipv4.conf.ppp0.rp_filter=2 sysctl -w net.ipv4.conf.ppp1.rp_filter=2 tc qdisc add dev ppp0 root teql0 tc qdisc add dev ppp1 root teql0 ip link set teql0 up ip route replace default scope global dev teql0 ip -6 route replace default scope global dev teql0