Firstly: Defining the Call to the Prayer’s Initiation
Iqamah linguistically: is the root of aqam. Other roots are iqam, maqam, and qamah. It is said a person does iqamah in a place if he remains in it for a lengthy period or takes it as an abode. A person does iqamah of the law if he upholds it; and iqamah of the prayer is to oft perform it, to establish it. To carry out an iqamah for someone is to call them.
Iqamah technically: is to worship Allah, exalted, with specific words when standing to commence the prayer.
Secondly: The Ruling of the Call to Initiation of the Congressional Prayer
The call to initiation is a communal obligation. If enough perform it, the obligation falls off the rest. This is the position of the Hanbalis, some Hanafis, and a position among Shafi`is. It is also the choice of Ibn Hazm, Ibn Taymiyyah, Ibn Baz, and Ibn `Uthaymin
Thirdly: The Ruling of the Call to the Initiation of the Prayer for the Solitary
The call to the initiation of the prayer is a sunnah, and this is by agreement of the four schools of jurisprudence.
Fourthly: The Words of the Call of Initiation
The words of the call to of initiation are said only once, except takbir in the beginning and end, and saying “Prayer is established”, is also said twice. Overall, these are eleven statements. This is the position of the Shafi`is, Hanbalis, Zahiris, a narration from Malik, the position of the majority of scholars, and the position of a group from the Salaf. It is also the choice of Ibn al-Mundhir and Ibn Baz.
Fifthly: What is Mustahabb for the Call of Initiation
It is mustahabb that the caller is upon purity. This is by agreement of the four schools of jurisprudence, and it is the position of the majority of scholars.
It is mustahabb that the caller stands, and this is by agreement of the four schools of jurisprudence.
3. Facing the qiblah
It is mustahabb that the caller faces the qiblah during his call. This has been mentioned explicitly by the Hanafis and Shafi`is, and it is a position among Malikis.
4. To not walk
It is mustahabb for the caller to not walk while giving the call. This has been mentioned explicitly by the Hanafis, Shafi`is, and Hanbalis.
5. The caller to the prayer is the caller to its initiation
It is better if the one who gave the call to the prayer to also give the call to its initiation. This is the position of the majority: Hanafis, Shafi`is, Hanbalis, and a position among Malikis. The majority of scholars act according to this, and it is the position of a group from the Salaf.
6. Swiftness  Hadr is speediness, meaning to be swift when giving the call to the prayer’s initiation.
It is mustahabb to be swift in the call to initiation. This is by agreement of the four schools of jurisprudence.
Sixthly: The Legality of Breaking between the Call to the Prayer and the Call to Its Initiation
It is legislated to break between the call to the prayer and the call to its initiation.  Scholars differed in terms of specifying the break between the call to the prayer and its initiation. As for maghrib prayer, then they viewed it as mustahabb to have a short break between the two, while still differing over what short means exactly. This is by agreement of the four schools of jurisprudence.
Seventhly: Continuity between the Call of Initiation and the Prayer
It is not a condition that the call to the initiation of the prayer is immediately followed by the prayer. This is the position of the Hanafis and Hanbalis, and it is the choice of Ibn Rajab, Ibn `Uthaymin, and the position of many scholars.
Eighthly: The Time When Those About to Pray Stand
1. The time when the congregation stands for the prayer if the imam is outside the mosque
If the imam is outside the mosque, then the congregation does not stand until it sees him. This is the position of the Hanafis, Hanbalis, and is attributed to the majority. It is the position of some of the Salaf and Dawud al-Zahiri, and it is the choice of Ibn al-Mundhir, al-Shawkani, Ibn Baz, and al-Albani.
2. The time when the congregation stands for the prayer if the imam is inside the mosque
The one who is about to pray may stand whenever he wants, during the call or after it. This is the position of the Malikis and the majority of scholars, and it is the choice of Ibn Baz and Ibn `Uthaymin.
Ninthly: Placing the Finger in the Ear During the Call of Initiation
It is not a sunnah to place the finger inside the ear for the call of initiation. This is explicitly mentioned by the Hanafis, Shafi`is, and the verdict of the Permanent Committee.
Tenthly: Answering the Caller
Scholars have differed over answering the caller during the initiation of the prayer according to two views:
The first: is that it is mustahabb to reply to the imam bby saying as he says, except in the Hay`alah when the reply is: there is no power or strength except through Allah. This is the position of the majority: Hanafis, Shafi`is, Hanbalis, some Malikis, and the choice of Ibn Baz and al-Albani.
The second: is that it is not sunnah to reply to the caller of the initiation of prayer. This is a position among Hanafis, a position among Malikis, a position among the Shafi`is, and the choice of Ibn `Uthaymin.
Eleventhly: Starting an Additional Prayer after the Call to the Initiation of a Wajib Prayer
If the call to the initiation of the prayer had been given, then no prayer should be performed other than the one initiated. This is by agreement of the four schools of jurisprudence,  Hanafis disliked this, and excepted the two voluntary units for fajr as long as he does not fear missing the congregational prayer. The apparent position of the Malikis is impermissibility, while Shafi`is view it as makruh. and it is the position of some of the Salaf.
Twelve: If the Call to the Initiation of a Prayer is Given While a Person is in Voluntary Prayer
The Shafi`is, Hanbalis, and some of the Salaf hold the position that if the call to the initiation of an wajib prayer has been given while a person is in a voluntary prayer,  Ibn Taymiyyah said: “If the obligatory prayer is to be called for shortly, then one ought not to initiate any voluntary prayer which would make him miss the start of the obligatory prayer. Rather, leaving it to make the start of the prayer is legislated, keeping in mind that adhering to perfection in obligatory acts is more praiseworthy than a voluntary act which may be fulfilled or made up another time.” Sharh al-`Umdah – Kitab al-Salah (609/4) he should complete his prayer  He would finish it relatively swiftly, making it light. Scholars also differentiated between whether he already prayed one unit, in which case he should finish it, and whether he did not, in which case he should break it. unless he fears he will miss the wajib prayer in congregation,  For Malikis, he would break it if he fears missing one unit from the obligation, and there are scholars who view breaking it if he fears missing the first takbir of ihram. in which case he breaks his voluntary prayer for the obligation.