Detecting carriers for mobile devices

1. A method comprising, by a computing device:

receiving a request for a multimedia object from a mobile-client system of a first user;

accessing SIM-card information associated with the mobile-client system;

determining a carrier based at least on a social graph information associated with the first user and the SIM-card information, wherein determining the carrier comprises calculating a probability score the mobile-client system is using a particular carrier by comparing the social graph information associated with the first user and the SIM-card information with a database of the online social networking system; and

sending the multimedia object to the mobile-client system in response to the request, the multimedia object comprising an advertisement that is customized based on at least the determined carrier of the mobile-client system.

2. The method of claim 1 , wherein the SIM-card information comprises an http-header indicating a carrier associated with a SIM card of the mobile-client system.

3. The method of claim 1 , wherein accessing the SIM-card information comprises:

sending a query to the mobile-client system for the SIM-card information; and

receiving the SIM-card information from the mobile-client system.

4. The method of claim 1 , wherein determining the carrier is further based on a carrier history associated with the first user.

5. The method of claim 1 , wherein determining the carrier is further based on an autonomous systems number (ASN) associated with the mobile-client system.

6. The method of claim 1 , wherein determining the carrier is further based on an IP address associated with the mobile-client system.

7. The method of claim 6 , wherein each carrier is associated with a range of IP addresses, and wherein determining the carrier based on the IP address associated with the mobile-client system comprises determining the range of IP address comprising the IP address associated with the mobile-client system.

8. The method of claim 1 , wherein the request further comprises an http-header, the method further comprising:

accessing a user information describing the first user;

determining one or more attributes of the mobile-client system based on the http-header and the user information; and

sending the multimedia object to the mobile-client system in response to the request, the multimedia object being customized based on at least the determined attributes of the mobile-client system.

9. The method of claim 8 , wherein the one or more attributes of the mobile-client system comprise one or more of programming language support, style-sheet language support, screen size, screen pixel density, keyboard type, location-services support, wireless communication support, image support, or video support.

10. The method of claim 8 , wherein determining the carrier is further based on one or more of the attributes of the mobile-client system.

11. The method of claim 1 , further comprising determining a connection-type, and wherein the multimedia object is further customized based on the determined connection-type.

12. The method of claim 1 , further comprising determining a connection-status, and wherein the multimedia object is further customized based on the determined connection-status.

13. The method of claim 1 , further comprising determining a latency-period, and wherein the multimedia object is further customized based on the determined latency-period.

14. The method of claim 1 , wherein customizing the multimedia object based on at least the determined carrier comprises including content associated with the carrier in the multimedia object.

15. The method of claim 1 , further comprising:

accessing a social graph of an online social network, the social graph comprising a plurality of nodes and a plurality of edges connecting the nodes, each of the edges between two of the nodes representing a single degree of separation between them, the nodes comprising:

a first node corresponding to the first user, the first user being associated with the online social network; and

a plurality of second nodes that each correspond to a second user associated with the online social network;

wherein determining the carrier is further based on user information associated with the first user.

16. The method of claim 15 , wherein the user information comprises a user profile of the online social network corresponding to the first user.

17. The method of claim 15 , wherein the user information comprises information describing one or more friends of the first user corresponding to one or more second nodes, respectively, and wherein one or more friends of the first user have mobile-client systems with one or more carriers, respectively.

18. One or more computer-readable non-transitory storage media embodying software that is operable when executed to:

receive a request for a multimedia object from a mobile-client system of a first user;

access SIM-card information associated with the mobile-client system;

determine a carrier based at least on a social graph information associated with the first user and the SIM-card information, wherein as part of the determine step the carrier calculates a probability score the mobile-client system is using a particular carrier by comparing the social graph information associated with the first user and the SIM-card information with a database of the online social networking system; and

send the multimedia object to the mobile-client system in response to the request, the multimedia object being customized based on at least the determined carrier of the mobile-client system.

19. A system comprising: one or more processors; and a memory coupled to the processors comprising instructions executable by the processors, the processors operable when executing the instructions to:

receive a request for a multimedia object from a mobile-client system of a first user;

access SIM-card information associated with the mobile-client system;

determine a carrier based at least on a social graph information associated with the first user and the SIM-card information, wherein as part of the determine step the carrier calculates a probability score the mobile-client system is using a particular carrier by comparing the social graph information associated with the first user and the SIM-card information with a database of the online social networking system; and

send the multimedia object to the mobile-client system in response to the request, the multimedia object comprising an advertisement that is customized based on at least the determined carrier of the mobile-client system.

20. The method of claim 1 , wherein the social graph information associated with the first user comprises information identifying one or more friends of the first user within a social graph, and wherein one or more friends of the first user have mobile-client systems with one or more carriers.