Anonymous online services???

Why are online services allowed? The kind that allow people to send messages anonymous? I didnt even know there were services like that until this week when a family member of mine was hit by one. She said that she recd a text which was to her very hurtful, what made it worse was that the person claimed to be a member of her family. Yeah i know! That in itself shows it for what it is, if someone is going to do it anoymous then they are not going to be telling you where they are from. The fact that they claimed to be from her family is proof that its someone trying to create problems beween us. But what i think is really a problem is that she said that you cannot call them and find out who sent it. Why is this allowed? I really think there has to be a way you can find out, there has to be a way right? If anyone has any connections at all in how to trace it please let me know as i would like to help her find out who did this. She thinks its a male that did it, but i think just because of some things she said was on there that it was a female. I dont want to go into details of what makes us think that as of course without proof its just going to create more problems by going into it. But this type of thing really really makes me mad. She is preggie, on crutches due to knee problems and has a toddler to keep up with. The person behind it better hope i dont find out who it is, lol. I have never had any respect for people that do things anonymous, like ive said in the past, stand behind what you say or theres no value to it anyway. We do see this as someone trying to create problems within out family and if we can prove who did it, it will be dealt with. If that person is by any chance reading this. I DO know who you are, not hard to figure out. We already know how sick in the head you are. Yourve proved that to us all year. Take our advice and leave our family alone. Use your time to focus on your own family.
But anyway if anyone has any advice on how we can trace this please let us know and i will follow though. This has caused stress for someone that our family all care about and someone that has done nothing but done the total opposite of what that text suggested to her. She was there for me though all the hard times with my mum and there for me the day she passed away and arranged all our air travel (not easy for so many of us last min and with one of us in hawaii) and has always put herself out for us all. If i can help her figure this out i would love to more then i can say. I am totally disgusted that there are services out there that let people do this without any trace of them, there has to be a way!!!!!!!