Network Security for Telecommunication C

I need help with security needs for telecommunication company.
we secured an appointment with the local phone company in Saudi Arabia and we should provide them with security solutions.
I need to know the followings if someone can help:
1- What are the usual security concerns for telecommunications companies
2- What kind of questions we need to ask them in order for us to assess their needs
3- Have any one worked in the area who can provide us with some insight
Thanks