You mean like The Master's Message (HP, p.81) in which you tag the "Sender" box before it is shipped out? Let me think about that...
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You could create new "Sender" boxes without a need for AC. So new box, touch it to the invested item, activate, and go. However see the section below.
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Concentration (with Maintains Concentration) would not be the best Duration. Firstly someone would have to be at the item every Sunrise and Sunset to keep the link up. To avoid that you would need to go with Constant, which is D: Sun, 2@day, +3 Environmental Trigger.
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Level would be 30 with Concentration (40, -15 for Touch, +5 MC) or 34 with Constant (40, -10 for Sun, +1 2@D, +3 ET). Since in most Saga you should be able to use Momentary not much of a savings. [Momentary effects can last a round, several published Momentary spells are designed to affect a spell cast the next round.]
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You would be stuck with a single AC link (see below) compared to the option of having multiple ones to choose from.
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If the link is somehow broken then a new "Sender" has to be sent by the Covenant to reestablish the network. So subject to failed upkeep (twice daily) with Concentration and the actions of hostile forces.
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It is an always up link that goes into the Covenant (or where ever you store your invested device). Granted they still have to penetrate your AotH but you can do some nasty low level stuff like set a fire. Sending out an always up and already established IT is a security concern.
While you could do it, I would not recommend it. Its only real advantage is a slightly lower total level if you do your enchanted item right, while having a few drawbacks.
You can get "Multiple Links" in a single enchanted item. There are a couple of ways to do this though they need to be decided upon during the design phase.
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Multiple fixed AC during construction: You could make them as something like individual signs on the item. Make the activation something like touch one and say a word. The one you touch is the AC used for the effects.
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AC Slot: Design the item so it has a slot in which an AC can be placed. This is a little more fiddly since you are dealing with multiple separate items. However you don't have to fix a bunch of AC at the time of creation. In fact you don't have to create any before the enchantment can begin. This also has the advantage of using non-fixed AC for at least the time they remain an AC.
You can find multiple examples in my Covenant's collection of Enchanted Items thread, not just for teleportation items but things "alarm bells", "communication devices", and "spy devices".