Telecommunications providers should be more diverse, as in allowance of CLECs, as well as wireless/satellite/etc providers. WiMax is a very empowering technology, as is GSM in general. BurningMan and other events have setup GSM towers using very little, inexpensive equipment.
Fiber and the standard T1/SONET hierarchy allow for all kinds of diversity in paths and equipment. SONET especially has BLSR (2x and 4x), which are bi-directional line-switched rings. Fully Optical Networks have additional capabilities -- I remember Cerent/Cisco in particular defining PPMN (path-protected mesh networks), which have evolved in several ways through various Optical Network equipment providers.
The best way to ensure diversity is to lean on the documentation and processes around provisioning. LinuxHomeNetworking did an article on relocating data centers that covers Data Circuit Provisioning. In the article, a few terms are described, such as the DLR (or design layout record/report). The DLR is basically documentation demonstrating the diversity of telecommunications connections. Customers (or potential customers) need to ask for their DLRs and make sure that what they are buying is what they want.
Additionally, BGP Multihoming and mesh networking protocols can provide redundancy at the higher network layers. ATM had first made this possible with PNNI, but MPLS replaced it with constraint-based routing. Wireless mesh networks have increased in popularity over the years. The MIT Roofnet Project (SrcRR) became Meraki Networks. LocustWorld MeshAP took off for many years in the UK. Small branch projects like the Seattle Wireless and Portland Wireless groups utilized many disparate mesh technologies (HSLS was very popular). A few commercial providers in these areas also celebrated success.
To best answer your question directly, I think you'll enjoy the resources available at the Wireless Networking in the Developing World website.