Can I record the bookings I make over the phone or offline in the same software, so everything sits in one place?

Yes, in most setups you can. Travel agency software is usually built on the understanding that not everything comes through a portal, so there is normally a way to create a booking by hand for the trips you arrange over the phone, by email or face to face. Once it is saved, it sits in the same booking list as the ones your website produced, and the customer record shows the whole history together.

The way it works is that you pick the type of service, such as a flight, a hotel, a transfer or something you have put together yourself, then type in the supplier, the passenger names, the travel dates, what you paid, what you charged and the supplier's confirmation reference. From there the booking can usually flow into your invoices, vouchers and sales reports just like an online one, so your month end totals cover everything your agency sold rather than only the automated part.

There are honest limits worth knowing. A manual booking only holds what you type into it, so it will not update itself if the supplier changes something, and it cannot warn you about a cancellation deadline unless you record that date yourself. Which service types you can choose from, and whether you can bring older bookings in from a spreadsheet instead of typing them again, depends on your plan and on how your account has been set up.

The next thing to do is write down the kinds of offline business you handle most often, including anything unusual such as visas or rail, and check that each one can be recorded the way you need before you move your records across.