Did all the eligible voters who phone-polled actually vote?
Did they poll the way they actually voted?
Some people don't have two phones?
Can we trust that telegram doesn't have a flaw in the means by which it is measured? (i.e. register again with the same SIM, or something like that?)
It's nice that there is a phone number as validation, but this doesn't 'prove' anything.
Edit: I should add, apparently people are registering photos of their votes, which don't jibe with the tally, which is probably a much better indication of problems with voting [1]