I use A&A for inbound and freevoipdeal (PAYG) for outbound.
You said you use over 1000 minutes per month, is that calling landlines?
If you top up approx. £10 on Freevoipdeal, you get max 300 minutes per week of free calls for 120 days, measured over the last 7 days to landline destinations in the UK and 30+ other countries as well as free calls to mobiles in US and Canada . The calls to destinations not included in freedays is also quite reasonable, e.g. calls to UK mobiles at 1.2p per minute. Same if the 120 days are up or if you exceed the 300 minutes per week.
FreeVoipDeal | Cheapest rates available: Free Calls!
www.freevoipdeal.com