Android :: Poll Phone Number In Android / Identity / International Dialing Codes?

Background; I am in the process of writing an Android messaging application that needs to know the current user's phone number. This is then used to connect to other users using the application. My application relies on looking up the user's number from Android's Settings -> About Phone -> Phone identity -> Phone number (this can at times be blank.. but that is a separate problem). I am assuming that the above Phone number contains the user's full number. ie, my UK Android phone shows my number as: +447832xxxxxxxx, where 44 is the UK's international dialing code and 7832 is the operator. Is it safe to assume that all Androids phones would include the international dialing code, which starts with +? I would be indebted if any Android users could have a quick look at their Android settings and confirm whether Phone number is displayed as +international code+operator+number, i.e. US Android sets start with +1xxxxxx.