I treat telepathy just like speaking; it doesn't require an action to establish a link or whatnot. I could see requiring one if you want to start telepathically 'talking' to someone you can't see to represent the "mentally searching them out" part, and similarly if they go beyond 100' and then come back the telepath doesn't have any way except for normal sight or keeping trying to reach out telepathically to know that.

In general I agree with @PeterSeckler, interpret it whatever cool way you want and if PCs are finding some way to abuse it, toss in some limiters. I know a group would love a "can't be overheard and can work through walls" tactical coordination tool, but a little bit of "the rogue got dragged out of range/fell through a long pit trap" and "a psionic monster that can overhear telepathy just heard all your plans" from time to time compensates.

The psionic power mindlink does exactly what you want: It's low level and works on any creature that has an Intelligence of 3 or higher. (As long as you spend the points to make it work on an unwilling target.)

And most importantly:

You can communicate telepathically through the bond even if you do not share a common language.

As a backup option, as long as you can touch the ice toad, you can cast tongues on it. Tongues doesn't require a willing creature, so as long as the ice toad fails its will save this should allow it to speak to and understand you.

This spell grants the creature touched the ability to speak and understand the language of any intelligent creature, whether it is a racial tongue or a regional dialect. The subject can speak only one language at a time, although it may be able to understand several languages.

This won't allow it to speak to other ice toads:

Tongues does not enable the subject to speak with creatures who don’t speak.

So if you want it to be able to speak to other ice toads, you'll have to cast the spell on them too.

There is one other fly in this ointment:

The subject can make itself understood as far as its voice carries.

This is potentially problematic, because if ice toads don't have a voice (which may or may not be the case), they will be able to understand you but not speak loud enough for you to hear. This will enable any communication method that relies on the creature understanding you, and might allow communication methods that rely on the creature having a language. (Depending on whether understanding every language counts as "having a language"; I can't find a rules definition of what that requirement actually entails.)

Alternatively, with one-way communication established, you may be able to talk it into accepting a telepathic bond or some other method that relies on having a willing target.