How can I take an interview while at a job that tries to prevent interviewing?

I get it. The threat of being unemployed is daunting, especially when you have a family to provide for.

However, you're allowing them to take advantage of you and imagining consequences far worse than are likely to be.

Next time you schedule a phone interview, call in sick. Take the day off.

The next day walk in, say you're really sorry but you just couldn't make it into the office.

Unless you're completely of no use, they will not fire you. If you are of no use, you have other problems.

They have spent time and effort hiring you. They have spent time and effort training you (or at least paid you while you were learning about the code base). This is time and effort they would need to expend again if they fire you.

While Maryland is an at will employment state, there are federal laws that regulate the workplace and I'm pretty sure being fired for missing a single day of work would be good grounds for a wrongful termination lawsuit. (I'm not a lawyer though).

Additionally, you'll get about $1,600/mo in unemployment insurance if you do get let go for this reason. That should give you some time to find a new job..

If taking a sick day is too much for a first step, trying going out for a short walk and don't answer your phone. If they ask, tell them that you were on the phone. That should be the end of the conversation.

If the company is trying so hard to keep you that they try to keep you from interviewing, why would they fire you or persecute you if you did do an interview?

The policy that you must be at your desk 9 to 5 sound like it is motivated by something else, e.g. a need to ensure that they can bill a government contract for all the hours in the day for all the "resources" on the project. The government contractor mindset doesn't so much care whether you a working as whether you are billable.

The person is clearly valued. Maybe they are not aware of it. If they are under-valued, they will be pleasantly surprised at how their employer responds (hint: movement towards parity).

Stop caring. Go for an interview. You are not property. You are merely selling your labour.

If you don't smoke, pretend you do. Go out for a smoke break at interview time. Only have that "smoke" a half a block away from the office so you don't get caught out.

Does this kind of awful behaviour exist in other companies, or other industries?

In other words, how surprised are people from Maryland / the USA to hear of it?

Spend a little time learning how to negotiate and interview. You don't have to become and expert, but there are some simple concepts that will boost your confidence tremendously. Greater confidence and negotiating skills will mean you'll never feel trapped in a job again. It will be too easy to find greener pastures.

This is nuts. How many people work at this place?

If true, this sounds like the kind of company that needs to be named and shamed and investigated.

Sounds a bit like slavery. Try to save up and then get the ACLU or some human rights organizations involved.