First you will be lucky if most people on this forum even know what you are asking for.
This is old method of doing this mostly only seen in china.
Your first issue is you must have all the details of which channels are mapped to which sites. In most cases it is not a single 64k channels it is groups and the channel numbers do not necessary match on each end. Even worse is when multiple e1 are delivered at the central site and channels are bonded between them.
With a simple layout like this you would want to use static route. The only reason to use OSPF is if you had a larger network this was connecting to. In that case your configuration must know all the area numbers are area types to correctly configure it. The hard part is not adding this it is knowing how to integrate it into your existing OSPF. If this is the only network then OSPF configuration is trivial and unneeded...ie static is simpler.
I need detail configuration of Channelised e1 with OSPF configuration between HO & 6 Branches.
Please help me out, i really appreciate.