I have the simplest of samsung flip phones and suddenly text messaging failed - can't send or receive. Calls still work fine.

SOURCE: text messaging

Check the message center no .. it might me wrong !!! Call ur customer care and verify the message centre no!!

SOURCE: ENV CAN NOT MAKE or receive text or calls

try to reset your phone back to default by going to your menu then going to settings and tools then to phone settings then down to security type in your password it might be your last 4 of your phone number then to reset default

SOURCE: Nokia 2310 suddenly stopped sending text message

If the SIM works fine in other phones, there is a phone issue. See if you're eligible for a warranty replacement (eligible if purchased new from AT&T within the last year or if purchased refurbished from AT&T within the last 90 days). If ineligible and you have insurance, use it... there will be a $50 deductible applied to your next bill. If ineligible and you haven't got insurance, get a replacement through somewhere like ebay or craigslist, upgrade (never EVER use wirefly or amazon, trust me) through AT&T preferably, or purchase a gophone (AT&T prepaid) from walmart, walgreens, wherever (If you go to RadioShack, they'll do everything for you). You just put your SIM in it and it will have your phone number and contract information... you don't have to sign up for prepaid service.

SOURCE: Samsung Star Multimedia Messages Won't Send

hi dear friend YOU ONLY SEND AND RECEIVE TEXT MESSAGES OK. contact your vendar for mms messages.

SOURCE: My phone won't send text

check sms setting