What 3rd Party SMS service do folks use for sending mass / bulk texts to their clients?

What 3rd Party SMS service do folks use for sending mass / bulk texts to their clients?

Last month we ran a promotion and marketed it via 4 social media posts and two email sends. Then, we supplemented the campaign with sending SMS messages to our clients from the client re-engagement report. 3 of us divided up the report and pasted the message in the Jobber text thread, changed the first name of the recipient and sent it off to about 600 clients out of ~5,000. It took 3 days... No, not 8 hours a day, we had other things on our list. And when someone responded positively to our message asking for a quote our service manager would go into quote/sales mode while we kept sending. It was brain numbing, but effective. For February, which historically only brings in half or less of the revenue we make during a typical in-season month we almost doubled it. It was our best February ever.

The takeaway: Texting works (when done right). For the time it took it will be worth it to spend money on a third party service and press send once, instead of 600 times. 

So, please share your experience with bulk SMS services- good, bad, meh... I would love to know. Thanks! 

~Kyle Klevjer