So, you're an Inquisitor, patrolling this world for heresy/further heresy. As an Inquisitor, you might have access to any data caches on the planet, and you might have information nets/contact networks that can find out almost anything, but what happens when you need to know something about someone "from out of town"? Inquisitors might be detail-oriented, and have memories like a steel trap, but even they can't remember every person they've ever seen, or they haven't maybe ever seen them, before. Say you are investigating a fellow Throne Agent, or maybe a Rogue Trader? Any information about them when not on this planet is, well, not on this planet. How does the Inquisitor get the info they need, the details about who that is, what they believe, what they've been up to?

I suppose this might just be me harping on the 40k verse for not having e-mail, but do they really grab an astroapth, ask him questions pertaining to sensitive matters, wait for him to broadcast, wait for the message to pong it's way across the sector, get translated, someone go find info, repeat, and then have the astropath, or some scribe/servitor take dictation on the possible volumes of sensitive info the other end might be sending? Sit around for a week, to a month, waiting for an Inq ship to bring a data cache? It might help maintain the grimdark feel of the difficulty the Inquisitor's job contains, only barely containing evil, even with all their resources, but how do they make it work? For the Inquisitor whose network goes beyond a single world, maybe even a single solar system, how do they maintain their contacts as a viable advantage?

I had this issue, too, in Rogue Trader, when I wondered if worlds had a few extra astropaths, just because, to send messages, or how did the Rogue Trader keep up with all of his assets, opportunities, and foes? If you were to play Lure of the Expanse, did fate just ham-fistedly deposit you on Footfall in the right time frame for the Fortelling? You, and half a dozen others? Did one of your contacts hear about it, and dispatch an astropathic message, which might take a while, and then you need to warp jump, and system travel, for about a month? With the Rogue Trader so often out on the frontier, starting new colonies, looting old tombs, and mapping the tattered edges of the map, how does the dynasty stay in contact, and how do business opportunities find them? The big difference here, though, is that the Rogue Trader's job might be seen as selfish; a plan to get rich, and be a pirate lord, thinly veiled under service to the Emperor, but the Inquisitor's job is often seen as safeguarding the entire Imperium. In your games that don't only cover one world, with no threads that reach beyond it, how do they handle this sort of thing?

Well, this is my personal interpretation incoming.

There are plenty of Astropaths out there, at least for the Very Important People of the Imperium's purposes. A good rule of thumb would be if a ship is capable of Warp-travel then it generally has at least one Astropath aboard and if a planet provides a tithe, it has an Astropathic Choir at the least.

I would guess that a number of Astropaths are picked up by the Left Hand of the God-Emperor explicitly for their use, inducted/trained with the basic Inquisitorial ciphers and stationed in Inquisitorial holdings or released back into the general populace of the Astropath community in order to have the opportunities to pick up on and relay messages. There'd be some means of identification for agents of the Inquisition to spot such sleeper cell Astropaths. These wouldn't be for your personal and single-network communications, but for large scale warnings and less-valuable communiques. This doesn't account for the Astropaths individual Inquisitors cultivate/recruit on their own in the field.

The party's Inquisitor in my game (an Inquisitor Lord of the Ordo Xenos in all but name, he tells people to shut up when they try to give him titles but is easily recognized as the most influential Ordo Xenos member in the sector) has cultivated such ties across the sector, even some outside; he's a fan of finding Astropaths, abducting them quietly, inducting them into his communication network, then letting them go back to work. This Inquisitor also snatches up tithes when available and generally has an Astropath in his pocket or under his network's control on almost every planet of the sector, as well as on a number of voidships. Each planetary or ship network has a 'brain' cell, which collects information, produces intelligence, helps direct local cells (investigation, research, castigation, etc.) and sends valuable data up the totem pole using this Astropath. These networks are moderately self-sufficient with a half-dozen cells incorporating trusted Interrogators, some of whom are entrusted with recruiting and inducting local talent to prevent attrition and maintain or increase their influence.

Important data that is sent up to higher cells is generally of no less significance than planetary scale or regarding a Peer of the Imperium; the Inquisitor will generally send support of some sort to the location if there is a problem, or if he's feeling bored go there himself. If the information is better off in the hands of another Ordos, he gives them a truncated version of the situation so as to avoid revealing his assets (some Inquisitors in the region tend to make use of disposable agents and see everyone elses' agents the same way).

He has enough clout and authority amongst his brethren (he's a rare moderate and mediator between Radicals and Puritans) to help connect their networks with his, thus making sure everyone wins a little (but him a lot). It isn't a perfect system, but he works with the materials provided.

If he has a request for information, the Inquisitor has his personal Choir send the (encrypted) message to all relevant cells; if that doesn't turn up anything in the month or so it takes, then he starts asking colleagues and peers through a similar method; extremely important requests might go to everyone at once since waiting too long can end poorly.

Now, not every Inquisitor works like this one. Some focus on individual planets; Inquisitor Lord Leonard Jecchinarus of the Ordo Hereticus basically runs a minor crusade in a cycle, for example. Besides his informants throughout the sector, his retinue is always focused on the same planet. He shows up with a legion of agents, infiltrates society for a year or two while acting discreetly and evaluating everything, then brings out the regiments of witch-hunting acolytes and starts doing mass purges of mutants, witches and heretics until he is satisfied with the results. He then packs up, leaves a few informants behind to monitor things as well as a clean-up crew, then travels to the next planet on his roster.

Others dedicate themselves solely to the planet they are on, ingratiating agents into every facet of that society, able to watch and find every threat... But limited in scope.

A few even eschew large systems, basically going around as Knights Errant or the Marshals, leaving squires/deputies in their wake after they deal with the threats they come across.

The power of Rogue Traders should be enough to get them an Astropathic Choir or two along with individuals, with the value of their Dynasties being a good way to estimate how good their communications are.

Sorry for the multi-post.

Also note that there are people (outside the inquisition) whose entire job revolve around knowing who's who - organisations like the Famulous Orders of the Sororitas, bonded emissary and courier guilds, administratum bodies who might be involved in dealing with rogue trader's - who (somewhere in the files) will have records on any rogue trader dynasty who've operated within the sector. These people will pay good money to know, and to know about, important persons right across a region of space, because contacts, discretion, family secrets and influential relationships of Peers of the Imperium are their day-to-day business. All you have to do is 'persuade' them to share the information with you.

"Where the rogue trader goes when outside the sector" is something you would need to insert an agent into the dynasty to know, but the movement of voidships within a sector is the sort of thing you can find out from administratum records. As noted, any major voidship probably has an astropath, and any major world many. A worthwhile standard communication between worlds of a sector is the arrival and departure of a ship, if only so that a ship which departs is missed if it doesn't arrive....

Alternatively, bring it with you. A well-organised librarium of useful information on archaeotech data-storage devices could probably fit aboard the hold of a supposedly merchant void-ship. Combine with a larger-than-advertised astropath choir and you have the ideal mobile base of operations for the investigative-minded throne agent.

So, you're an Inquisitor, patrolling this world for heresy/further heresy. As an Inquisitor, you might have access to any data caches on the planet, and you might have information nets/contact networks that can find out almost anything, but what happens when you need to know something about someone "from out of town"? Inquisitors might be detail-oriented, and have memories like a steel trap, but even they can't remember every person they've ever seen, or they haven't maybe ever seen them, before. Say you are investigating a fellow Throne Agent, or maybe a Rogue Trader? Any information about them when not on this planet is, well, not on this planet. How does the Inquisitor get the info they need, the details about who that is, what they believe, what they've been up to?

My take on it is that the Inquisitor is investigating something (for example; the disparitions of blonde people in between 13-23 year's old, and then discover a link with an external force, or not). Then he follow the trail of this external force, put people to scrutinise any details of its presence here, and follow. If the Rogue Trader seems to be working for a dark agency, the Inquisitor will follow, infiltrate, confront him, until he has his answers.

Yes, it's better if you know a lot about the people you're investigating on, but you can go straght ahead for the intel, getting it yourself as an Inquisitor. You infiltrate his ship, you send acolytes through his crew, you follow him on his endeavours, and you get your intel. If you're sure the problem on the planet you're investigating have a link with said exterior agent, you then concentrate ressources on him and, as a bonus, you hope to receive the astropathic call with all the intel you want about him.

For the Inquisitor whose network goes beyond a single world, maybe even a single solar system, how do they maintain their contacts as a viable advantage?

I had this issue, too, in Rogue Trader, when I wondered if worlds had a few extra astropaths, just because, to send messages, or how did the Rogue Trader keep up with all of his assets, opportunities, and foes? If you were to play Lure of the Expanse, did fate just ham-fistedly deposit you on Footfall in the right time frame for the Fortelling? You, and half a dozen others? Did one of your contacts hear about it, and dispatch an astropathic message, which might take a while, and then you need to warp jump, and system travel, for about a month? With the Rogue Trader so often out on the frontier, starting new colonies, looting old tombs, and mapping the tattered edges of the map, how does the dynasty stay in contact, and how do business opportunities find them? The big difference here, though, is that the Rogue Trader's job might be seen as selfish; a plan to get rich, and be a pirate lord, thinly veiled under service to the Emperor, but the Inquisitor's job is often seen as safeguarding the entire Imperium. In your games that don't only cover one world, with no threads that reach beyond it, how do they handle this sort of thing?

It's just hard logic; be it the Inquisitor or the rogue trader or the Imperium as whole, they all have great ressources at their disposition.

Worlds are protected by agents of said organisation (inquisition or rogue trader, and generally, imperium) and these ressources are supposed to suffice between visits/reinforcements.

You don't have to be able to send your intel efficiently as an acolyte cell, you have to gather it and intervene with the ressources you've got when a problem arise. You send your results by astropath and your Inquisitor will decide what to do with it when he come back, if he does. Same for the Rogue Trader, he doesn't have to be in communication with them often, he orders them to stockpile the ressources, the riches, all of his due from the colony, and when he comes back, he takes what's his and go away.

The only real problem of all this is when you've got a problem so big that you need immediate help, that you're screwed. And the problem existed in medieval times and exist in 40k and will certainly exist if one day we are scattered across the stars as a specie.

That's why the Imperium like big and hard things; they put their ressources and hope that they suffice for the long period it will take to come in reinforcement.

In the end, the Inquisitor or the Rogue Trader just does this, they act, they put safeguard and when they come back, they hope it worked and intervene depending on the situation.

I hope this helped you. That's the way I portray it in my games.