You don't need to build nsmap
manually.
Replace following lines:
nsmap = {}
for ns in root.xpath('//namespace::*'):
if ns[0]:
nsmap[ns[0]] = ns[1]
with:
nsmap = root.nsmap
Another way to get text of specific element (using xpath):
>>> root.xpath('.//SCPP:RESP_HDR/Status/text()', namespaces=nsmap)[0]
'00'
>>> root.xpath('.//SCPP:RESP_BODY/Seed/text()',namespaces=nsmap)[0]
'001335834994'