UCAS released the A level results to universities on Sunday 11th. If you meet the offer, then the place is confirmed automatically.
As soon as the grades are released, universities start going through applicants that miss their grades and deciding whether to accept them, reject them or offer an alternative course.
This process starts with the firm offers, if a place is rejected, the insurance place goes through the same system.
At my uni, we always ensure all our applicants have a decision on track before the Thursday, although other unis like to keep people hanging on (which is really annoying for us if we have a potential insurance place decision to make).
If Birmingham has rejected, there is little point ringing them unless you have new information (eg planning on appealing), as they will have already considered the application.
Whether or not we will take a student with missed grades depends on a number of factors. These include:
Number of places available
Total UCAS points (we offer on grades, but look at total points when making missed offer decisions)
Which A level has missed (so a dropped grade in chemistry is less important than a dropped grade in history for social sciences)