telnet client application

we have a customer who wants us to build an application . We normally develop desktop applications or web applications with c#. But customer wants us to run our application on telnet. So We want to work with an expert on telnet so we will give mockup screens to her/him so s/he will develop application.. We will develop backoffice and write SqlServer storedprocedures... S/he will only develop front office but will call sqlserver SPs and will set some data on screen from the data fom SPs. At the end we will change SPs to adopt business logic.. We expect the programmer to give us a running application integrated with SQL SPs and to give us the source code with documentation of developed c# telnet code..