The honest answer to this question is ask your GM.
Because what you want to do is up entirely to GM prerogative.
Zhangar's got it spot-on.
This isn't a game-mechanics question. It's a how-does-the-GM-want-to-run-the-story question.
That said, total devil's advocate... in theory the sending spell might work. But if I was a deity, I'm pretty sure I'd let those calls just go to voicemail.
I thought that's what spells like Commune and Contact Other Plane were for.
There is no straight percentile roll for "contacting your god". But there are a number of spells that work that way - more or less.
Spur of the moment intervention can be handled as follows: If the character beseeching help has been exemplary in faithfulness, then allow a straight 10% chance that some creature will be sent to his or her aid if this is the first time the character has asked for help. If 00 is rolled, there is a percentage chance equal to the character's level that the deity itself will come, and this chance is modified as follows:
Each previous intervention in [sic] behalf of the character -5%
Alignment behavior only medial -5%
Alignment behavior borderline -10%
Direct confrontation with another deity required by the situation -10%
Character opposing forces of diametrically opposed alignment +1%
Character serving deity proximately (through direct instructions or by means of some intermediary) +25%
As far as I know - there is only one way to 100% guarantee that a deity will notice you in Pathfinder.
Gate.
Calling Creatures: The second effect of the gate spell is to call an extraplanar creature to your aid (a calling effect). By naming a particular being or kind of being as you cast the spell, you cause the gate to open in the immediate vicinity of the desired creature and pull the subject through, willing or unwilling. Deities and unique beings are under no compulsion to come through the gate, although they may choose to do so of their own accord. This use of the spell creates a gate that remains open just long enough to transport the called creatures. This use of the spell has a material cost of 10,000 gp in rare incense and offerings. This cost is in addition to any cost that must be paid to the called creatures.
10,000 gp - the cost of the spellcasting - and as noted they don't *have* to respond.... but it is a valid way to know for sure that you made the deity think about you for at least a faction of a second.
Outside of that it's 100% GM whim if your deity even knows the prime material exists.....
You know, if you are talking about metaphorically b***h-slapping your deity to get what you desire, you are better off not getting any attention. If you think your deity is your b***h, you have more problems than we have any desire to go into.
As the consensus, this is firmly in the GM's purview, but if you approach the issue as the 1st post, you are begging to be taught just who is the b***h.
In WotR for a demigod you want to call to help you fight directly it's a d100 check and success chance is your cha score - double if you have a special connection to them - this is mythic so maybe max 80% chance to respond, but you at that point have seen the demigod in person
so when praying is not enough, and you need to grab the attention of god.
now is that a charisma roll? is there a way to improve that roll without killing something or yourself?
with all that praying that is going on and you need to get your call across to god. like all the gods are gathered in a room bound and gagged and about to be executed. how would you b+~!# slap your god and let him/her know that you're an open vessel and willing to take their place. you know that kind of important of a call. how would we go about doing that?
I'm assuming any situation in which a god is bound a gagged and about to be destroyed will also include a situation in which followers of such a deity have been cut off from communicating with the deity.
Simply put you don’t. You are the worshiper not the deity so what you want is not that important. Any circumstance where a deity is helpless a PC is going to be completely useless. In pathfinder deities are not stated out for this very reason. Compared to any kind of true deity nothing your character can do will make a difference.
Step 1, become a god in your own right.
Step 2, will yourself to the place in question.
Step 3, talk to the desired god face-to-face. They'll even care what you have to say, since you're a peer!
Good luck not getting bound, gagged, and executed yourself.
I usually just send a text.
1-800-Dial-a-Deity
Some of us have omniscience, you just need to accept we're ignoring you.
Part of being one of the faithful is that you need to accept the message
"Your prayer is important to us. No servitor is available for direct intervention at the moment. We are experiencing very heavy prayer volume at this time, due to a star going nova in quadrant 64. There are 42,976,912,765,815 sentient beings ahead of you. Expected wait time is 3 centuries, 10 years, 7 days, 5 hours, and 20 minutes. You may continue to pray, or hang up and try again later."