Sinch (formerly CLX Communications) offers a range of SMS messaging services, including the former mBlox, which was acquired in 2016 and serves as a component of Sinch messaging services
[Sinch is] a great SMS aggregator offering full performance with short code messaging. They are very helpful with the certification process and their after launch production support is extremely good too, even going above and beyond after hours in the rare situations where it could be required. My only area of concern is pricing as I've seem some competitive pricing from other service providers that are quite popular too.
I feel that Sinch does not have very well customer support and documentation. Despite having a strong and durable platform, Sinch brings on a very huge learning curve as very limited knowledge articles are provided on their website. Since this is a new tool, there are very limited online communities/ forums supporting this tool and hence, a newbie will definitely struggle in deploying/ using Sinch in my opinion.
None, this was our very first SMS service platform and it is doing great. Despite a huge learning curve, this platform has made its position and now serving all of our employees.