Just hang up and do not ever call that number back.

It is a complicated cell phone scam or virus which allows unauthorized $4.99 charge to your cell phone once it gets a hold of your phone number.
Here's more info:
http://forums.redflagdeals.com/help-mystery-cell-charge-2030-a-1301319/4/

21.10.2014. Have just received 2 calls in quick succession from this 0203 code. Someone foreign speaks very slowly against background noise. I hung up both times. Obviously a scam. Delete number and do not phone it back!!

I received a bill from Rogers for $4.99 for calling 2030 but I did not call or text this number at all. And Rogers is not accepting any responsibility and will not waive the unauthorized charge. Any guidance on this issue.

I just received a charge for $4.99 on my Bell account.   This is very poor customer service if they are aware of this, probably not leagal either.

Call from 2030 not wanted think a scan