we were pleased with their service. This was back in 2003-2004. They were very knowledgeable about the space, and we learned a lot from them. They handled all of the short code provisioning for us...for a fee of course. I think OpenMarket is offering more boxed solutions instead of the raw network access for third party developers.
Our software operated on a dedicated short code provided by simplewire. At the time this was the only way (at least that we could determine) to get two-way sms functionality in application. It was very expensive and was around 98% of our start up cost. Nevertheless, their testing portal was slick and allowed us to test without incurring any cost (other than short code provisioning). I think the short code access ended up costing us around $13000 over the year the product was in production. It didn't generate enough revenue to justify the costs (mainly because i now think it was a bad idea), so we couldn't afford to keep it up.
On a side note, we had developed most of our application before finding simplewire using a GSM modem (~$200), a cheap cell phone with text plan (~$50) and an linux box running Kannel (
http://www.kannel.org/index.shtml). This setup allowed us to prototype on the cheap...though we all had sms plans to test against. This allowed us to test inbound sms messages against our app...you simply put the cheap phone's sim card in the modem, and send your inbound message to the cheap phone number...kannel links the inbound message to your app...easy and cheap way to test before investing in the short code.
