I have a 3g modem, from Orange. My lsusb output:

Bus 003 Device 004: ID 19d2:0031 ZTE WCDMA Technologies MSM MF110/MF627/MF636

So, the problem is that this modem is not always detected. For example when I turn on my notebook, I wait ~ 40 seconds and sometimes the connection appears in the connections menu, but sometimes not. Can anyone explain me what is the problem and how to fix it ?

Using Ubuntu 13.04 64

PS: Sorry for my english, I am from Romania.

Thanks.