Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Security threats in Prepaid Mobile   Recent communications environment significantly expand the mobile
environment. Prepaid mobile services for 3G networks enables telecommunication
to sign up new users by utilizing the latest in converged billing technologies.
The worldwide mobile communication market is exploding, and 50 percent of
subscribers are expected to use prepaid billing . Prepaid services are driving
mobile communication into emerging markets such as South America, Eastern
Europe, Asia, Africa and Gulf Countries. Prepaid phone service requires a user
to make payment before calling. It is quite common to get prepaid SIM cards on
every major Network. This paper discuss about various prepaid techniques,
challenges and countermeasures in prepaid mobile communication system .

5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th