first check the sip phone CSS

for testing mae sure the sip phne and line CSSs same as the cisco ip phone as you mentioned the cisco one can make call out

next what type of voice gateways you are using ?

i will assume you are using h323

if this si the case debuge voip dialpeer

and make a call from the sip phone just to see the call reaching the gateway or not

if you see result that means the call reaching the gateway if nothing that mean your issue still in callmanger side

after that try to assine MTP resources to the GW MRGL and reset the gateway from call maager

good luck

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