We have a great deal of experience bonding multiple 3G channels across multiple different carriers, using WiBE. With it's revolutionary antenna technology, WIBE also boost throughput, even before bonding is applied.
Bonding across EE and 3 is currently our most frequently deployed set-up, as this provides a good compromise between speed and resilience. We find Velocomms a reliable and cost effective provider of the bonded solution itself -> www.velocomms.com
For more information, see one of our customer stories here, from our Sister company -> http://rangexd.com/deltenna
If you have any further questions, drop me an email to email@example.com
and I'll get back to you.
(Marketing at RangeXD)