There's not nearly enough information in your post:
- what 'trouble'?
- are you using the stock Messaging app?
- is the problem with all of your contacts or only some?
- what is your cellular signal like (how many bars)?
- what firmware?
- if your contacts send you an SMS, do you receive it?
Sent from my rooted, debloated, deodexed Sinclair ZX-80 running CM 10.2 using Tapatalk 4