@BitMaxz, from their FAQ:
This means that he can’t reuse the number, even if it’s with Telegram. If he needs to login to his Telegram account again and doesn’t have a device logged in (e.g he uninstalled it, his pc/phone broke, etc), he will probably get locked out.
If you just use the service from activation tab you can use their service once but if you rent them you can use them until the rental time expired. Quote
One number can be used for one service only once, but can be used for another services.
This means that he can’t reuse the number, even if it’s with Telegram. If he needs to login to his Telegram account again and doesn’t have a device logged in (e.g he uninstalled it, his pc/phone broke, etc), he will probably get locked out.
Take a look at this link http://smspva.com/arenda.html
Hushed - mentioned above - charges $4/month for 150 SMS and 50 minutes OR $10/month for 250 SMS and 100 minutes. Meanwhile, smspva charges $0,5 per day ($15/month) and he’s locked to the choosen service (Telegram). If he chooses a USA number, it’s double the price ($30 month).
. They ship to you a SIM for free, it's a prepaid phone number, so if you want to keep the number just verify your ID, otherwise if you need it once only then don't verify your ID and they will close the line after a period like 2 weeks. 
