i've been on google for awhile trying to find a consensus as to whether or not a sim card has any affect on 2g/3g connection, data download speeds, etc.
from what i gather, a sim card has no effect, its all in the phones capabilities. the sim just carries your account info for authentication. also newer sims have more memory for contacts and messages.
the part where i have some confusion is the SIM card versus UICC cards running SIM app on it for 3g. i assume older 3040 sim cards are not UICC cards?? and 4000 series are UICC cards?
anyways, if i use a 3040 sim instead of a 4000 sim in a 3g berry, it will not limit my voice/data speeds at all. i will be able to do voice/data at the same time.
i have to say YES the SIM card does affect the phone speed, in my case two days ago, my bold lost the 3G connection and stuck on EDGE, then reading in a venezuelan forum i noticed that this happened to others people and the solution was to change the SIM, even when the old the SIM used to work normally on 3G suddenly just stuck on EDGE, i've been looking for an answer but noone knows.
