You can sue everyone "shotgun" method, just name them all in the complaint, each one under a separate "count". You have the obvious direct breach of contract claim against the "small business" you describe; then, you have a two possible theories of recovery against the other entities: (1) a claim of "quantum meruit" or "unjust enrichment" based upon your having provided valuable services to them or on their behalf, and it would be inequitable for them to keep the benefit of those services without paying for them; and (2) "detrimental reliance" or "primissory estoppel", which means you would have to have rendered performance under your contract in reliance upon a promise or representation of the other entities that they would pay the "small business" the amounts necessary to pay you to perform your contract. The latter theory is a little dodgy, in that you would need to have had communications directly with the other entities (you cannot rely on those entities' promise to the small business; rather you need to have relied upon a promise or representation made to you directly from them). The defendants can all deny liability and move to dismiss, but they'd have to prevail, and rather than incur litigation expenses, they may settle and pay. Also, even if your direct claims against the other entities are disallowed, the small business can/should file cross-claims against both of them for breach of its own contract and for contribution in the event you prevail on your breach of contract action. By suing them all up front, you will force them all to engage in the litigation. If all this sounds somewhat complicated, it is. If your claim is worth enough, it would pay to use an attorney.
Generally, unless you have a contract with a firm or person you cannot successfully sue.
Certainly stop doing the work immediately. But unless the amount owed you is small it is time to hire an attorney. They might be able to pressure your prime contractor to sue the college, which in turn might then sue the telecom.
Licensed in Maryland with offices in Maryland and Oregon. Information here is general, does not create a lawyer-client relationship, and is not a substitute for consulting with an experienced attorney on the specifics of your situation.
You should hire counsel to write a demand letter to the party with which you have a contract and sue them if they don't pay you what you are due. Contact me for a free evaluation of your claim.
Mark L. Rosenberg is an attorney admitted to practice in the State of Maryland and the District of Columbia only. This answer is meant to be for educational purposes and no attorney/client relationship is intended or created by this answer. You should consult an attorney in your jurisdiction for information on your case or claim.