"By the end of second week of May we will be issuing the purchase order to these companies. Since this is a huge order, a lot of details need to be worked out and we are currently doing that," BSNL CMD A K Sinha told PTI.

"Once PO is issued and the companies accept the order, they have to produce the bank guarantee and then we issue the Advanced Purchase Order for the first phase of the 45.5 million lines," he added.

When issued, this would be the world's largest ever single tender for 45.5 million lines of GSM telephones.

By December, the first phase of BSNL's GSM expansion is expected to be in place. The first phase is for 17.5 million lines while the second and the third phases are for 14 million lines each.

With this, the pressure on BSNL's mobile service will ease off and quality of service will improve. In March, the PSU topped the charts in subscriber addition with 1.98 million GSM subscribers, increasing its total user base to 2.74 crore (27.4 million).

The order got delayed by six months since as one of the disqualified bidders - Motorola went to court challenging the tendering process. The process could start only after Motorola withdrew the case.

Telecom Minister Dayanidhi Maran has announced a 500 million telephone target by 2010 and also on an average 3 million GSM additions per month from 2008-2010.

Any further delay in the project could not only result in BSNL losing its third position in terms of mobile subscribers, but also derail the Minister's vision.

As per the terms of the tender, Ericsson, which had emerged as the lowest bidder, will get 60 per cent of the 45.5 million lines while the second lowest bidder Nokia would get the remaining 40 per cent.

BSNL has already stated that, if necessary, it could scale-up the tender size by 50 per cent and possibly even 100 per cent after the initial orders have been placed.

The vendors will be allowed to import only for the first phase. From the second phase onward, the specified core components of the network will have to be manufactured in India. Also, the minimum value addition of indigenisation of such core components must be 30 per cent.