Here are some more ideas (any excuse to repeatedly post a cap of Lolly...). I thought the Party Girls screen had a great look, but I reckon viewers expect a 'full screen' display for the girl(s) now - especially with rival channels offering 'full screen' as standard.
I like the transparency idea, but the lack of a predictable background can reduce the impact/visibility of the text. In other words, if you've got white text, and the set behind it happens to be white, the text becomes less well defined. So another way you could get round the limited space is to have more of the graphics sharing screen areas with each other on an alternating toggle loop. In the following example I've moved the contents of a promotional black box so it shares with the main telephone number. I know it's probably not considered desirable to have the phone number taken off screen, but if you set it on, say, a five second on/off loop with some important text, viewers would still always have it to hand. Plus, I think the 'animation' in that area of the screen may draw more attention to it. You could even have different colours for different message-types to draw more attention still. One big advantage of two pieces of info sharing space is that some viewers may notice things they wouldn't normally look at. For some, reading the phone number can draw attention to the text, and for others, reading the text can draw attention to the phone number. You may even find that having the main number sporadically disappearing off screen could generate urgency among viewers to dial it more quickly while it's there. The mobile number would still remain perpetually. Anyway, this pic shows the standard black box...
And these two show how the black box (now a blue box in this instance) could toggle with the main phone number...
My next suggestion would be to move the rolling pic promo so it shares space with the 3G promo, and move both the pics/vids video inset
and the accompanying pics/vids black text box into its place. So you then have this...
The vid inset and its accompanying black text box (both now bottom right) essentially fit into the space of one box because the text is on a transparent layer which fits over the video inset. The text overlap is enough to save space, but not enough to completely obscure the visual promo. This also seems to link the text with the 'product' better than writing it in a separate box. I've now shown the main phone number and 'blue text box' on a 50/50 fade to indicate they're still sharing space (but both would obviously show clearly in their allotted timespans). The above example actually has the equivalent of three black boxes on screen, but looks much less cluttered and, to me, digestible. If you feel that the bottom right is a bit inconspicuous as an area for the current vid/pic box, you could alternate its display with exclamation marks every so often to attract attention (see next pic). I think this would be better done at random than on a loop though, because people get used to loops. I think random change has more power to attract attention than positioning, and, to an extent, than size...
The only technical change I'd make to pop-up ads would be to keep them clear of the T&Cs. The T&Cs might be ignored by 99% of viewers, but if someone does want to read them, it's important that they can. Here's how Barry Scott might revise the BS Xtreme ads. To me, red looks so much more impactive than dark grey. That's not a 'white box' by the way. It's Lolly talking...
As regards the full screen ads, again I'd ensure they don't obscure the T&Cs, and on another better-safe-than-sorry note, I'd check that any alternating displays were okay with respect to viewers with photosensitive epilepsy. I'm sure you have to do stuff like that anyway, but I don't want to be suggesting stuff which could potentially compromise a viewer's safety. Anyway, all the best with the development. And just to be clear, this is not a competition entry - it's an attempt to help keep the girls full screen with a minimum of intrusion from the graphics.