"We are looking in total at the demobilisation and reintegration of 182,900 adults across east, north and south Sudan, not including any possible operations in Darfur," said Adriaan Verheul, chief of the UN programme supporting the government-run scheme.
"This will make it the biggest DDR operation in the world."
The programme is a key part of a 2005 north-south peace deal that ended one of Africa's longest civil wars, in which over 1.5 million people are estimated to have been killed and another six million displaced.
Run jointly by northern and southern government commissions, the numbers will be split equally between the northern Sudan Armed Forces (SAF) and the southern ex-rebel Sudan People's Liberation Army (SPLA).
"It will serve [the] stabilisation of peace in the country," said William Deng Deng, chairman of the southern DDR commission, in recent comments to Sudan's official news agency SUNA.
Initial lists run to 50,000 names, and planning maps mark out proposals for work to begin. Child soldiers are the first focus, with some 1,300 already demobilised.
In addition, 2,900 ex-rebels in eastern Sudan, who fought for a decade in separate battles before a 2006 peace deal, have taken the first tentative steps towards peace.
"The aim is to turn soldiers into civilians able to make enough money to take care of themselves and their families without their army salaries," Verheul told IRIN.
The head of the northern DDR commission, Sulaf al-Dein Salih, said progress was going well in the east, expressing "satisfaction" at the disarmament process "in both north and southern Sudan".
Staggered demobilisation scheme
Under a staggered demobilisation scheme, soldiers put forward by their commanders will be assessed, electronically registered and given medical checks at special centres.
They will also get a US$400 lump-sum payment, 10 weeks rations for a family of five, and a package to help start a new life as civilians, including basic tools, a mosquito net, plastic sheeting and a wind-up radio.
Later, each retiring fighter will receive reintergration support worth $1,750, including vocational training to learn a new career, or backing to establish a small business or farm.
"It's a political process with security objectives, but uses development methods and has a humanitarian impact," said Verheul.
Darfur poses threat
Building peace in Sudan is a slow and often shaky process. Many worry that continuing war in the western region of Darfur could destabilise peace efforts elsewhere, especially with potential genocide charges looming over President Omar al-Bashir.
National elections are due in 2009, followed by a 2011 referendum in the semi-autonomous south on whether it should become fully independent.
Tensions remain high, especially in flashpoint border zones, and former enemy armies are watching over their neighbour's capabilities with concern, nervous of reports that the other is rearming.
In the grossly underdeveloped south, an area about the size of Spain and Portugal combined but with virtually no tarred roads, militias and heavily armed civilians still dominate many regions.
Even apparently basic tasks, such as transporting fighters to demobilisation centres, will pose giant logistical challenges.
"You cannot demobilise a soldier and then put him out on the street without the means to survive and a minimum of dignity," said Verheul.
"Reintegrating former military personnel is often difficult; they may not find the new life appealing, or they don't have the right education for civilian jobs - or there might not be enough jobs for them on the market."
Guaranteed funding needed
Experts say it is vital core funding is guaranteed before the bulk of demobilisation begins, warning that ex-soldiers not provided with a new means of income could themselves pose considerable risks.
And the programme is far from cheap - costing US$385 million for the crucial three-year reintegration phase.
The cash is planned to come from the UN, international donors, and $45 million from Sudan.
Officials are upbeat about the prospects: "Policies are in place, planning is under way and the funding for some initial steps is available," the UN's top envoy to Sudan, Ashraf Jehangir Qazi, said in a recent report.
A pilot project for adult fighters is due to start in November in Blue Nile State, with around 1,000 soldiers from both north and south expected to take part.
"If successful, this will be repeated in other areas," Verheul said.
However, around half of the first batch of 50,000 put forward are war-wounded or disabled, a point some critics say means that active military forces will not be reduced.
Verheul dismissed this, arguing there is a need to treat all ex-combatants with respect, to encourage those still able to fight to find a new income.
"No parties in a DDR programme come forward with their best soldiers first," said Verheul. "One must build confidence, to get a more serious reduction in military forces later."
Many Sudanese who were affected by the war are hoping for the best. Like many whose villages were destroyed in Sudan's 21-year civil war, tea seller Mary Jok knows the cost of conflict.
"There's been fighting most of my life," said the 40-year old widow, who ekes out a living from a tiny street stall in the Sudanese capital, [Khartoum] where she fled a decade ago. "My daughters died and my sons were taken to fight," she said.
On the scattered stools in the dust around Mary Jok's tea stall, customers say there is both hope and cynicism at the programme.
"We have heard grand plans before," said Ahmed Ali Mohammed, a teacher. "But we want peace to develop Sudan. We need it to work - there are too many people today who know only how to fight."