MMS service piggybacks on the data service you use, Tink. Take look at for example Celcom's settings. It uses the same APN settings for the Celcom3G to send MMS through. Turning 3G services off disables the ability to send these multimedia message service. Text-based messages uses the normal GSM network. You cannot send MMS through GSM telephony network.

EDIT: This is unique to the iPhone only. Other phones may be able to use WAP-based services for this, but even WAP employs GPRS as its mode of transport.

This post has been edited by stringfellow: Jul 2 2009, 09:03 PM

@Tink
Yup. If you turn off the mode of transport, the "passenger" will go nowhere.

It all depends on the data carrier the MMS piggybacks on and what you set on the APN window. If your setting is via 3G and you turn that off, it'll go nowhere. If you want it to go via the slower data carrier, you need THAT data carrier settings on the APN window.

It was easier last time because there was no other mode of transport for these MMS other than WAP/GPRS. Now with 3G, you need to specify which data carrier you are sending it on.