(ShareCast News) - Shares in BATM Advanced Communications plunged as the telecoms provider posted an unexpected loss.At 13.18 BST shares in the telecoms and medical provider were down by 8.84% to 16.75p. BATM swung to a pre-tax loss of $1.97m from a profit of $203,000 in the first half of last year.Revenue declined by 16.05% to $47.6m from $56.7m, which BATM attributed to foreign exchange rate fluctuations, as the Euro and Eastern European currencies weakened against the US dollar.The company's biomedical division, which made up 56% of revenue, reported revenues down by 12% to $26.5m to $30.2m.Revenue in the telecommunications division, which made up about 40% of total revenue, was down by about 20% to $20.89m from $26.2m.However, the company said gross margins had improved from 23% in the first half of 2014 t0 25% for the first half of 2015.BATM said it expected to report full year profitability in line with market expectations."Full year 2015 revenues will be adversely affected by foreign exchange fluctuations, although the Group cannot predict the extent of the impact and is taking steps to mitigate it," BATM said in a statement.FinnCap, which held a 'corporate' rating on the stock said it lowered its revenue forecasts to $105.7m from $114.5m to take into account the exchange rate impact.The brokerage said its profit expectations were unchanged and target price remained 20p.