MMS Gateway Provider with PHP API, URL Callbacks, etc

[alaffodsend]

Similar questions have been asked a few times, but I was unable to find the answer I needed in those other questions, so here goes.I am looking into integrating MMS messaging into a website and I seem to be hitting a wall when it comes to which provider to use. SMS only gateways seem to be prevalent, but MMS gateways with a useful APIs looks to be a different story.Specifically I need the following:

• A good PHP based API -OR- a navigable HTTP Post structure so I can CURL to them
• Ability to both send and receive MMS messages through the gateway
• Direct URL callbacks so that my server can be updated in real time instead of polling for updates
• Global reach (I know this one is tenuous at best but I need as many providers in as many countries as possible)
• Cost, while not a HUGE factor is important in testing.. I need to be able to trial the system to be sure it works. I would like this to be under a few hundred bucks.

So far I have looked into:

• OpenMarket - no URL callbacks that I could find
• GlobalSMS - they aren't even able to successfully send an SMS to my iPhone in the US, so I'm not trusting them with my global MMS FAIL
• Clickatell - They require a $1,700 US short code (which takes 2-3 months to set up) in order to even test their system against a US phone. FAIL
• Mogreet.com - US only mobile messaging, though looks like an easy integration for the US market

Any insight or further advise would be very helpful. We are also looking into Mbuni and NowSMS to send them directly through a GPRS modem on our servers, but I have a feeling the gateway will be the way we have to go in the end.Thanks in advance for any help you can give, I'm relatively new to mobile messaging integrations, so some good advise here is welcome!