How can i set my sonim phone so i can send and
Hi,am sure it's related to your sim card (network), not your samsung cell phone. In most cases, regarding mms messages, the problem is from the Service Operator. Have you tried the sim card on another phone? If not, remove the sim card, insert it on another phone and try sending a message from another mobile to you number, or you can do it in vise versa by inserting another sim card on your mobile.
If you can't receive mms messages even it's inserted on another handset, then you need to call the customer care of your Network Operator and tell them your problem, they will help you fix it immediately.
You can check the message center number, but I don't think it's very much important in your case, well, if you wanna try, just check the text message settings and verify that the message center number (which is currently in use) is the same number which is on another phone with the same network (the other sim should be of the same network in your area). If it's different, make the changes and save the settings. Also disable the "Receive Via" or similar settings.. (I can't recollect the exact settings as i don't have the same model with me, please excuse me for this.).
if the same sim card doesn't receive mms messages using another handset, don't bother to change the settings or to make any changes with it, first call the customer care and verify from them, you may make mistakes instead of fixing it.
Have a nice day.