I have a strange problem here on my grand. After rooting i've flashed some roms before using carbon rom 4.4.4. The weird part is everytime i tried send sms it directly failed but not with other 3party sms app (i tried textra and gosms). Any other rils are working fine as ussual (calls, data etc). Is this was a modem problem or something else?
Yes it is a RIL problem, kindly use some other modem, or radio. It will work. Depending on your phone. At times post rooting, the IMEI gets changed to 0, kindly check if it is 0, then flash a different modem, and it will work.
BTW, there is another solution, which might or might not work: Dry clearing the dalvik, and it works for few. (Sometimes, due to some apps dalvik over lapping causes the issue).