For some reason once the campaign is sent it doesn't start to send SMS right away it may take 30min to a couple of hours. It doesn't matter is your campaign is not urgent or emergency.
You have to upload your contact list for the specific campaign It seems that you can't just copy and paste the numbers for quick campaigns.
Even if the UX is undertandable, there is room for improvement.
I already pointed out this but basically we decided to go with SMS.to because 2 reasons:
1. It can be paid with paypal (first reason) we have some bad experience with other products because payment gateways may suddenly block your cards and you're unable to pay even if you want to use the service so when we saw that SMS.to has Paypal payment we just decided to go for this option.
2. You pay per message and not per contact this is ideal other platforms will ask you a monthly fee for marketing features that you're not looking plus paying per SMS or per contact we were just looking a straight forward software in order to send SMS campaigns.