Delay Tolerant Network (DTN) allows data communication in a challenged network situation. Originally DTN was developed to be used in inter planetary network. Later on researchers found it suitable for developing system to deliver public services to the people living in the remote part of the developing countries. In the DTN architecture designed by IRTF researchers considered the disruptions in the communication channels due to contact out of site, long transmission delay, environmental interference, etc. In the DTN architecture the bundle protocol (BP) was defined to work in-between application layer and transport layers. To ensure source to destination guaranteed point-to-point delivery of the bundles (here bundle is a chunk of data clubbed together to be transported as a unit) BP has provision for end-to-end acknowledgement implemented through hop-to-hop custody transfer and acknowledge mechanism. In this case the acknowledge bundles also travels through the same communication channel. With 6 billion subscriber base, mobile phone network with text and voice service is available almost every corner of the globe. In this paper we propose a small modification of BP for sending acknowledgements through SMS over mobile phone network. Considering the prevailing road transportation network in Bangladesh this process will improve the performance of delivery by reducing the average delivery time 50%.