Bug 1074601 - Take SIM card 2 into consideration when checking voicemail number

https://bugzilla.mozilla.org/show_bug.cgi?id=1074601
Is there a reason to use ```assert.ok()``` instead of ```assert.isTrue()```? As an onlooker from the outside, it threw me off for a moment. This isn't a big deal though, and I don't mind if you want to leave it as-is.