Undead Burg - When you're entering Undead Burg and just exiting the bonfire room.

Lower Undead Burg - Near the 2 shortcut from Undead Burg( above where the dogs are waiting)
and near the boss room.

Undead Parish - Near the sunlight altar, just by the bonfire, near the entrance to the bonfire near Andrei ( Where 3 undeads are waiting) and where you can summon Lautrec and Solaire for the boss fight ( just before the boss room)

Dephts - In the beginning, near the bonfire room and just before the Boss room.

Blighttown - Beginning of the map ( from Dephts), near the first bonfire, near the second bonfire and just before the boss room.

Demon Ruins - Near the first boss room.

Demon Ruins ( second part) - Near the bonfire and near the boss room.

Demon Ruins (third part) - Near the bonfire and near the boss room.

Lost Izalith - Actually, i don't know, but i think people place their signs near the boss room and near the bonfire in the lava( the one behind an illusory wall).

Sen's Fortress - The beginning of the level, near the bonfire and near the boss room.

Anor Londo - Near the First Gargoyle, near the Gwyndolin boss room, near the second Gargoyle, the third bonfire room (Where you can find Solaire), Near Solaire's Sign and just by the stairs leading to the boss room.

Darkroot Garden - just after you exit the room with the Titanite Demon, near the bonfire and near the boss room ( Where you can find Beatrice's sign)

Darkroot Garden (After the gate you need to open with the Crest of Artorias) - Just near the stairs and near the boss room ( Near the gates, actually, people are just wating to be summoned to pvp, near the boss room, people are wanting to help with the boss fight, but it depends)

Darkroot garden Basin - This place, i don't know, but i think it's near the Undead Burg shortcut( where Havel is waiting to smash you)

Catacombs - Near the first bonfire and near the second bonfire.

Tomb of giants - Near the first bonfire, Near the second bonfire and near the boss room (I don't know if in the beginning of the level, people place their signs there, but i have seen a lot of signs there)

Duke's Archives - After you get imprisoned by Seath, you need to climb a ladder, after you open the giant door, you can find signs there ( to open the giant door, you need a key, the key is up above the blue tentacles monsters, just go all the way down, you'll see it), near the third bonfire(obviusly).

Crystal Caves: Before the Giant Clams( People likes to summon near the third bonfire of Duke's Archives to Explore/Beat the boss, so i don't think that people place signs in the Crystal Caves)

New Londo Ruins - The beginning of the level ( near the undeads ), near the wooden bridge( after the 2 undeads and a pot/vase with a corpse), near the Beatrice's sign( It's easy to miss it, it's before the boss fog gate, turn your back from the fog gate and go ahead to the wall, to the right you can find a Darkwraith hiding and to the left, is the sign)

Painted World of Ariamis - Near the first bonfire

Kiln of the First Flame - Near the bottom of the stairs and near the boss room ( If you want tohelp with the boss, try placing your sign near the boss room, people often stays in the kiln to pvp, but depends)

Sanctuary Garden - By the bonfire

Royal Wood - Near the exit of Sanctuary Garden, before the Artorias boss room and before the Kalameet boss room.

Oolacile Township - Near the first bonfire( A high traffic for pvp, be wary, people summon people to pvp, not always)

Oolacile Township dungeon - By the bonfire

Chasm of Abyss - Before the boss room.

Northern Undead Asylum.
Firelink Shrine.
The Great Hollow( Sadly).
Ash Lake ( Very Sadly, would be a great place to fight).
Quelaag's Domain.
Valley of Drakes.
Firelink altar.
Oolacile Sanctuary.
Duke's Archives ( Just in the "prison" part of the Archives, if you open the giant door, past this part, you can summon and be invaded).

- To be able to summon, you need to be human.
- You can place your sign before and after you've defeated a boss, but you can't summon anyone.
- The boss area needs to be alive.
- You can't see any signs if you place your own.
- In New Londo Ruins, you need to drain the water first.
- In the Duke's Archives you need to encounter Seath in his room first and be imprisoned and you can't summon anyone near the "Prison" part of the Archives.
- Some areas ( Tomb of Giants, the entrance to Duke's Archives and the further part of Demon ruins) have a Golden fog, to be able to traverse them, you need to place the Lordvessel in Firelink Altar.